Seating Depth

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Wm Cook posted this 3 weeks ago

This is a pretty broad topic but I assume that most people, including myself have biases we bring into the initial bullet seating depth on all “new” or “new to us” rifle/barrel. What’s your starting point before you start to go further in or further out and how is it impacted by bullet design?

I guess this is more directed to long guns and shooters looking for small groups but any opinion is valuable. Thanks, Bill.

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RicinYakima posted this 3 weeks ago

Using conventional cast bullets and lube, I start with the top driving band touching the lead/origin of the rifling. The only time it is not used is with a bullet with a bore riding nose. Then I start with the nose definately engraved checked with black marker. 

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Little Debbie posted this 3 weeks ago

I use the Stoney Point (now Hornady) seating depth tool. It allows you to find where any bullet touches the lands. I adjust from there depending on what I’m trying to do. I generally like ammunition to fit in and feed from magazines, so seating depth some time becomes moot as an accuracy variable.

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John Carlson posted this 3 weeks ago

I use a cleaning rod with a flat jag.  Measure the distance from the bolt face to the muzzle.  Insert the bullet and measure from the tip of the bullet to the muzzle.  This gives me the minimum OAL.  Same as Ric for bore riders.  For tapered bullets I'll try seating longer until there is light resistance when closing the bolt.  I haven't found a sweet spot or a sour spot within those parameters.

Holding public office should be viewed as an obligation to serve, not an opportunity to rule.

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Wm Cook posted this 3 weeks ago

Rick for the top driving band to touch the lead/origin of the rifling the free-bore would have to be large enough in diameter for the driving band to pass through in order to reach the leade/lands wouldn’t it?

I’v had two new Savage .308’s in the past year and both free-bore’s measured .308. The length of the free-bore is .120 on the one I’m working with now. At .120 the leade begins to form the lands.

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RicinYakima posted this 3 weeks ago

I have never had that issue, as the Savage FP rifle I have has a free bore of .310" I size to the next larger 1/2 thousandth larger. I use SAECO dies that come in 1/2 thousandths. 

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Wm Cook posted this 3 weeks ago

My FP has a free-bore of ~.3085 measured with both a pound cast and a chamber side tamped seating of an unsized bullet.

So the front band of my 311299 is seating against the wall at the end of the chamber. The seating depth variable I have with this chamber/mold combination (bore-rider) is how much crush I put on the driving band as it hits the end of the chamber before the free-bore.

The crush can be see with damage to the driving band on dummy rounds as well as with felt bolt resistance as John described.

I can jump it, kiss it or crush it into the free-bore. Or at least crush it until the neck tension allows the bullet to slip back into the case.

To be honest I’m a little bit squishy about seating out to where “light resistance is felt when closing the bolt” or “into the lands until you see engravings “. The person doing the hand-loading, the bullet taper (non-bore-rider) and/or the hardness of the alloy used makes this seem awfully subjective.

I’m crossing over from jacketed benchrest and in that discipline we know exactly where “jam” or “push back” is and best accuracy is found within .009” of “jam” position on barrels with less than 600-700 rounds through them.

I’ve talked to a couple guys who shot at the Nationals and they described the neck tension they used as light. Light to the point that it almost sounds like each round seats itself as the bolt closes.

I got a lot to learn.

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RicinYakima posted this 3 weeks ago

Cast bullet shooting is an art, not a science. Your cast bullet will become a wad of bubble gum upon ignition. 

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Wm Cook posted this 3 weeks ago

Probably a lot of truth to that but I nearly busted a gut laughing when I read your response. I just gotta laugh at myself once in a while. Thanks, Bill.

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4and1 posted this 3 weeks ago

Aint touching any of this............

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Geargnasher posted this 3 weeks ago

Cast bullet shooting is an art, not a science. Your cast bullet will become a wad of bubble gum upon ignition. 

 

Actually, the bubblegum phase happens much farther up the bore, likely an inch or more depending on the load.  Once the bullet moves and encounters enough resistance from engraving to increase the powder gas pressure beyond the ultimate strength of the alloy, the bullet base can begin to rivet and/or bend in the throat.  

The less "jump" or "run at the throat" that the bullet has, the higher the initial pressure and more steep the pressure curve.  An analogy is an air or refrigerant compressor starting against a full load versus against no load due to a check valve and relief valve.  More inertia from the bullet accelerating prior to taking the rifling form and less engraving resistance reduces bullet distortion, which is why relatively soft powder coated bullets with a tapered, self-aligning nose shape sized smaller than throat entrance diameter can be fired with full charges of rifle powder at maximum loads with decent accuracy and no riveting of the bullet base.  Pressure may reach 55K psi but the bullet is 3" down the bore and running away from the gas at many hundreds of feet per second squared before that pressure level is achieved, so the bullet is fully-contained in the bore and has nowhere to go but straight ahead.

The same principles of jump, self-alignment, sizing, and ductile alloy can be applied to ordinary, lubricated cast bullets, but it is trickier and has lower limits than the powder coat allows.  Still, if the bullet is raking off a bunch of metal on the abrupt throat entrance angle because it is too big, or is cast of a very hard alloy and jammed hard against the ball seat, the base will rivet and then draw down through the funnel of the throat, often not in any semblance of concentricity, balance, or squareness. 

I say all that to recommend never sizing larger than throat entrance diameter, never jamming a cast bullet hard into the ball seat, never use hard, brittle alloys, and avoiding perfectly-matching bullet/throat angles which bring a sudden increase to engraving resistance and spike the powder pressure against the bullet's base.  I know this is contrary to everything ever done in cast benchrest shooting, but it works very well in conventional, production rifles. 

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freebullet posted this 3 weeks ago

Err..uh... sometimes a little jump aint bad thing.

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Larry Gibson posted this 3 weeks ago

"The less "jump" or "run at the throat" that the bullet has, the higher the initial pressure and more steep the pressure curve."

That is the theory that has been around for as long as I remember.  The analogies supporting it, for the most part, all sound reasonable.  However, I have not been able to verify higher pressure occurs and/or a steeper pressure curve in actual pressure tests with cast bullets seated firmly into the leade or seated off the leade any reasonable distance.

A cast bullet, even a "hard" cast bullet, is much softer than a jacketed bullet.  The pressure needed to swage down and engrave the lands into the bullet is much less.  That swaging down and land engraving happens very early, at the beginning actually, of the pressure rise.  It seemingly, so far at least, has little if any measurable effect in the pressure or pressure curve with normally sized cast bullets that are not larger than the chambers throat.

LMG

Concealment is not cover.........

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45 2.1 posted this 3 weeks ago

Not everything (common knowledge or otherwise) one sees , reads and hears will get you what you want. Let the target decide.

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Wm Cook posted this 3 weeks ago

Not everything (common knowledge or otherwise) one sees , reads and hears will get you what you want. Let the target decide.

Agreed that you need a number of groups shot consecutively under real or simulated match conditions to see the effects of COAL changes.  My initial post was to see if there were any prejudices that you bring to the loading bench on the first attempt at developing an accurate load.

Cast bullet shooting is an art, not a science. Your cast bullet will become a wad of bubble gum upon ignition.

Maybe sometimes we mix the definitions of learned skills and art.  To a newbie, laying bricks may look like an art, but for most, not all maybe, but for most people if they put in the time and effort they can become average or maybe even good at laying bricks.  Some may think that casting quality competition bullets is an art.  But maybe we aren't giving enough credit to the individual that worked in the field long enough that skills were gained (trained or self taught) that enabled them to exceed. Just look at the results of the Nationals this year the the number of sub 1" group aggregates that were shot.  Look at all the .5's that were shot in the unlimited class.

When it comes to the performance of a mechanical object (mold, chamber, leade) science may have its part to play.  Larry is the only person I know that has can measure chamber pressure.  If jumping to jamming shows no significant effect on pressure some would have to give credit to that.  Maybe n my old age I'm getting more cynical about the use of the word "art" as if there are some things that only some can achieve.  If I think the numbers are gathered correctly I take that as a solid foot hold that I can build on.  And absolutely no offense to Geargnasher.  I've been reading you post for years and you have helped me an others more than you could possibly understand.

My motive is cast accuracy.  I believe it was Ken (if I am wrong and it wasn't Ken I apologize) who said that accuracy is defined in the first inch of travel.  If I remember correctly, and I'm paraphrasing, if the necks are turned, the case is neck sized the anchor points of the tension of the bullet in the case and the tension of the grip in the leade/lands will at least start the bullet in the right direction. 

My personal opinion is whether you call it art or learned behavior that's were the proper bullet seating depth comes into play.  I was just wondering if there was a tendency to self seat the bullet or were you just short of sticking in the lands.  Sorry for being lengthy.  And I apologize if I offended anyone. That was not my intentions. Thanks, Bill.

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RicinYakima posted this 3 weeks ago

Bill,

 "Some may think that casting quality competition bullets is an art.  But maybe we aren't giving enough credit to the individual that worked in the field long enough that skills were gained (trained or self taught) that enabled them to exceed."

That is the definition of a manual art. 

Science is "knowledge about the natural world that is based on facts learned through experiments and observation." It has to be 100% repeatable by anyone doing the same experiments without regard to place or time. Cast bullet shooting isn't there yet.  

IMHO, Ric 

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John Alexander posted this 3 weeks ago

I agree with both Bill and Ric in the two posts today. I also agree that that there is little scientific method applied to improving cast bullet shooting.  But that isn't because shooting cast bullets is  somehow different from other areas where applying the scientific approach to figuring out truth from myth has allowed great strides and great improvement.

The reason that there few instances of scientific methods being used to improve results is that cast bullet shooter, in general, aren't interested in doing experiments and repeating other shooters experimental results to sort out what thing might improve performance.

Larry's post above, by using a scientific approach to find the truth about an aspect of CB shooting, discredits a perfectly reasonable sounding theory about pressure rise. These things can be done -- we just don't generally do them, and when they are done we tend to disregard the results and go back to our previous belief.

Instead of experimenting with enough shots fired to have repeatable results most CB shooters would rather rely on three other approaches to try to improve.

1. Seek perfection with absolutely perfect bullets carefully sorted by weight, careful powder weighing, elaborate case prep, indexing bullets, cases and even primers, etc.

2. Depend on old rules handed down as the conventional wisdom. A perfectly perfect base is needed with sharp edges even when covered with a gas check. Don't let the base of the CB hang below the neck in the case.  Make sure your rounds are concentric. Make sure your crown is perfect. The way to improve your groups is to eliminate fliers -- believe that small groups don't have fliers without ever looking at them. Find the sweet spot for your rifle by ladder testing with a series of single five shot groups. Tune your load to your rifle by depending on single three shot groups being a valid measure for what the load will actually do in a match.  

3. Use logic without checking your assumptions. Think real hard and reason out what happens to a cast bullet from case to target. Reasoning that since the muzzle is the last thing the bullet touches, a less than perfect crown will cause inaccuracy. Reason that variations in bullet weight or variations in case weight (thus volume) obviously will affect accuracy.  Reasoning (without considering the numbers involved) that variations in neck tension affect accuracy.

None of these three approaches will help us improve what we know about CB shooting, nor shrink our groups.  Many of the above have been shown to be worthless more than once starting with Dr. Mann 120 years ago and by others since then using a scientific approach. However, the typical CB shooter disregards information that shows that what he had been told by good shooters and believed up until now is false. Worse than disregarding experimental information he is often hostile to it. We don't like to change our beliefs. This is just human nature and people in science or engineering research have to guard against it to make progress.

Until we change our approach there will be little improvement in cast bullet performance.

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MP1886 posted this 3 weeks ago

John I understand what you are saying. When you mentioned the crown of the muzzle it made me think of something not talked about much here. It's barrel turners.  I have a Mechanical Engineering friend who has a good friend that is a machinist and gunsmith. They came up with a barrel tuner/muzzle break. He was interested in how their tuner would work with my cast bullet shooting.  I done a lot of testing. This started when I bought a Browning A-Bolt Varminter with the BOSS tuner on it.  Now as compared to my engineer friend's tuner the BOSS is crude in only it's adjustments.  Well let me tell you that tuner sure shrunk my groups.  If you were adjusting it in the right direction you could actually see your group get smaller like you were dialing it in. Now on the my cast rifle with the tuner I came to the conclusion that the muzzle break portion of the tuner was doing something to the bullet so that it wouldn't group well.  Now let me stop there and tell this story.  I'm talking about an AR10 with a heavy barrel in 7.62 NATO.  When I built it I didn't put a flashhider on it at first. I made a thread protector.  I started developing cast loads and  had it shooting very well.  Then my flashhider came in the mail. I installed it and immediately my under moa groups went to 3 moa.  Just to make sure the hider done that I removed it and the groups went back to the tight ones.  Back on again they openned up. So that was it, no hider on that rifle. Back to the tuner/muzlle break.  We couldn't figure out why the break portion disturbed the bullet.  So my friend tells me to machine it off which I did.  Then it started working.  Tuners aren't going to make a miracle benchrest rifle out of your cast bullet shooting, but they do help and I believe more so then all the benchrest tricks with the case and such. Like I said tuners aren't talked much about here. 

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RicinYakima posted this 3 weeks ago

I did the tuner thing back in the '80's and '90's shooting BR 50 22's. Yes they work but only with a setting for one lot of ammo without changes. Some ammo was so inconsistent that the tuner never helped. Those pesky barrel vibrations keep rearing their ugly heads. 

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RicinYakima posted this 3 weeks ago

John, I was disappointed when no one expressed any interest on my work a couple of years ago on bad bullet groups. Five shot groups will be OK with some pretty ugly bullets. BUT using the old "tricks" more X's and ten's are scored if shooting for precision of each shot. Ric

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MP1886 posted this 3 weeks ago

I did the tuner thing back in the '80's and '90's shooting BR 50 22's. Yes they work but only with a setting for one lot of ammo without changes. Some ammo was so inconsistent that the tuner never helped. Those pesky barrel vibrations keep rearing their ugly heads. 

Rick listen to this story. There's this benchrest shooter gunsmith. He got to thinking one day about the forward action screw in the front receiver ring and also a gas escape hole if it had one.  He build a test 222 Rem, nothign fancy.  First he got an average group with the rifle untouched. Then he drilled a hole direct opposite of the forward action screw. I can't remember if he treaded it or not and of course the hole he drill was on top of the receiver ring. Back to testing and the average group got a little smaller. He done the same with the gas port hole and again the average group got smaller.  This all started when he was thinking about barrel vibration and how the holes in the receiver might affect them. There's many vibrations going on when we fire a gun. 

That Mechanical Engineer friend of mine was very interested in my cast shooting.  That is something he had never done. He asked me one day if I could take a picture of me firing that AR10 at night so he could see how much flash came out of the muzzle break portion of the tuner and also the muzzle. It happened to be a very dark night. I'm not kidding you there wasn't even very much of a glow at the muzzle!  He inquired about the load. At that time I was using a very slow surplus ball powder with a booster.  His exact words were when he saw my video "The Military would be interested in that"!!  It wasn't any reduced load either, it was a factory equivalent jacketed load. The total powder charge was 44.5 grains. The barrel length was 20 inches and plus the tuner/muzzle break which wasn't very much longer then a flashhider if that.  No I never shot the rifle without the tuner minus the muzzle breaker portion. I also don't have the video anymore. Maybe some night I'll do it again. I have no explanation for it and agreed with my friend that the powder charge definitely was totally consumed in the barrel, but yet why no flash?

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Larry Gibson posted this 3 weeks ago

Note, my post above references pressure only regards to cast bullet seating depth on or off the leade.  It does not reference whether accuracy is improved or not.  That is another topic for discussion. 

LMG

Concealment is not cover.........

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Tom Acheson posted this 3 weeks ago

I have to admit that I’m certainly not the sharpest knife in the drawer. The challenge I have with our hobby is trying to equate what we do to be able to distill it all down into a science. The reason….every gun is its own animal. Every gun responds differently to the never ending tweaks that we apply to them and what we feed them. With all the variables that we experience in the powders, primers and cases that we use, how do we “standardize” those characteristics into a commonly used formula?

 

If our goal is to develop a listing of do’s and don’t’s that can be applied to every situation, this elusive goal will be very interesting to see how it develops.

 

For years I’ve determined a cartridge’s OAL by tapping the bullet into the throat, run a dowel down the bore to contact the bullet. Mark the dowel. Remove the bullet, close the action and run the dowel into the face of the bolt, action, etc. Mark the dowel. Measure the span between the two marks on the dowel. START with that measurement in your first test loads. Then experiment with COA lengths plus or minus this initial measurement. 

 

An example…. 2005 I started using an XP-100 chambered in 30 PPC for the CBA BR matches. In 2005 it was deplorable (match results). In 2006 I altered the COAL AND the neck size bushing in the Redding die. Same powder and primers. Went to a 2-day Regional match @ Windhill in June and set (6) new CBA National Records, all in group shooting. I haver done well in score events. Moving that front rest constantly is something I have difficulty making work.

 

Another shooter using this same gun, load, etc. might not have had the same results. And that’s the other “un scientific” influence. We are a different person every day and maybe every target at a match. Shooter health, mindset, and most importantly bench technique, etc. produce and influence different results. 

 

I appreciate the drive to make things more “scientific” in our pursuit of optimum performance but how will that be accomplished? It has been said many times that two consecutive rifles off a manufacturer’s production line will not shoot the exact same load equally. The tweaking needed to search out that equality can be done but will invariably result in slight differences in the load details. And these differences may not fit into our “scientific formula”.

 

Like I said….not the sharpest knife…

 

Happy New Years guys!

 

Tom

 

 

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RicinYakima posted this 3 weeks ago

MP1886, when I built my 1000 yard Springfield, I did the same thing with the "Hatcher hole" on the left side, made an identical on the right side. Had the action converted to non-magazine and the Redfield base was cut to the same weight as the mag plug and the  base screwed and solder onto the action. Got a lot of information from Rifle Accuracy Facts by PhD Vaughn. Ric

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MP1886 posted this 3 weeks ago

MP1886, when I built my 1000 yard Springfield, I did the same thing with the "Hatcher hole" on the left side, made an identical on the right side. Had the action converted to non-magazine and the Redfield base was cut to the same weight as the mag plug and the  base screwed and solder onto the action. Got a lot of information from Rifle Accuracy Facts by PhD Vaughn. Ric

 

Cool Ric.  So when you done that with the holes did you notice an improvement?

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RicinYakima posted this 3 weeks ago

Yes, but I did several things at once; stiffened the action, put it in a newly designed wood stock (made to reduce vibrations), and a new Huber ball bearing trigger. So it is hard to tell which made what difference, since I was only looking for end results at the time. Who knew someone would want to know 20 years later?

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OU812 posted this 3 weeks ago

I thought all cast bullets should be jammed against rifling/throat for best accuracy. When you figure out how to shoot the cast bullet jammed into the lands...then you can experiment with jump to rifling. Should be easy to figure out after that.

Shouldn't we be talking about more perfect bullet fit and alignment. Happy New Year

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Tom Acheson posted this 3 weeks ago

Yes, bullet fit and concentricity relationship of the bullet and the bore, are what some would call “constants” in the equation.

Several of us would man a table at an annual gun show where the CBA was the main subject, not selling guns. We did have quite a few show attendees stop by and ask questions. In the early years, we would have example guns from each CBA BR match category along with sample targets. If a table visitor showed enough interest, we eventually brought up the fit and concentricity topics….and that’s when the eyes glassed over.

Eventually we stopped displaying the sample guns and targets. Why? The primary interest of table visitors was what alloy to use and how fast can the production rate of handgun bullets be improved? Most explained that they shifted from jacketed to cast, due to the perceived cost differential.

Back in the early 80’s and through the 2000’s, all I used were cast bullets at handgun silhouette matches, in revolvers and XP-100’s. Lots of good natured kidding from my shooting friends about using those “stinky” bullets. Maybe the lube smelled, who knows. But today some of those nay sayers are using CB’s. The reason…cost. This includes straight walled and bottleneck cases. In the bottleneck category there are MANY different case designs.

Question for the peanut gallery…the CBA has X members. What % are active match shooters? And what % are handgun shooters whose main interest is the alloy and casting speed and read the Fouling Shot, hoping there are more articles focused on those interests?

Tom

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OU812 posted this 3 weeks ago

Pre compressing and fitting bullet much like a pound cast helps lots. A die that squeezes bullet from top to bottom to more perfect deminsions. You can actually feel when the bullet stops being compressed in the press.

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OU812 posted this 3 weeks ago

Have you ever shot a pound cast? Neither have I. Stop and think

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Bud Hyett posted this 3 weeks ago

Question for the peanut gallery…the CBA has X members. What % are active match shooters? And what % are handgun shooters whose main interest is the alloy and casting speed and read the Fouling Shot, hoping there are more articles focused on those interests?

My main interests are single-shot rifles and double-action .45 Colt pistols. I shoot pistol to refine my eye-hand coordination. The Fouling Shot articles on .45 Colt and .44 Special are of constant interest to me.

I know the question about match shooters comes into view every so often. I read all the match reports to see if there are alternate powders to use in these days of shortages. And the articles on handgun shooting, especially hunting with handguns, are eagerly read.

I shoot the Elmer Keith Memorial Match near Spokane, WA whenever I can. The last few years have been cancelled due to COVID19. Targets are swinging steel, set at 140 yards, 200 yards, 250 yards and 600 yards. This is limited to iron sights and a maximum of a 10 1/2 inch barrel. It is a fun match with great people to talk with, I  also like the challenge.   

This question about percentage of shooters in the active match category may not be relevant today with the lack of primers. There is an active group of competitors in the Pacific Northwest and several are dropping out until primers are available at reasonable prices. We are seeing fewer competitors because they cannot reload for practice and do not want to shoot a match strictly for practice. 

Farm boy from Illinois, living in the magical Pacific Northwest

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Wm Cook posted this 3 weeks ago

That is the definition of a manual art. science is "knowledge about the natural world that is based on facts learned through experiments and observation." It has to be 100% repeatable by anyone doing the same experiments without regard to place or time. Cast bullet shooting isn't there yet.  IMHO, Ric

Ric, you're right.  I wish I would have said it that way.  I have a problem of getting my fur up when I hear anything that makes it sound like hand loading, casting, bench discipline and such as something mysterious or magical. 

John made the case that the foundation for cast bullet accuracy today is in large part based a blend of fact, assumptions, traditional means, harmless conventional wisdom and suppositions. A lot of us do what we do because it gives us confidence.  The downside is that some of it is pointless and its distracting us from what  might be important.

A lot of bubbles would be popped if we could combine our efforts and put it in hardcover.  Until then the contributions we make to the FS are that much more important.  And if you are new and looking to learn keep asking questions.  No chance you'll ever find someone who at one point in time didn't know the answer themselves but have since learned it. 

To the original question raised in the OP about jump, jam or in between for seating depth;  I start within thousands of sticking and work backward a few thousand at a time until the bullet base gets to the bottom of the neck or until accuracy fade.  Happy new year to everyone.  Bill.

 

 

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lotech posted this 3 weeks ago

I realize there will always be isolated exceptions, but I've seen best accuracy, regardless of bullet design, with the bullet seated to the point where it slightly engraves. "Slightly" has no standard definition and is interpreted differently by different shooters. "Slightly" to me means the bullet barely engraves and the cartridge can be extracted without any change in OAL (no crimping). 

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Tom Acheson posted this 3 weeks ago

Not wanting to hijack the original post but…..the long distance handgun steel plate match looks very interesting. It makes you wonder that after the rear sight is at its maximum upward travel, how do you know how much to “hold over” to hit the target at 600-yards? No kidding that this type of shooting is challenging!

My favorite rifle is a Sharps Model 74 with iron sights and black powder. The CBA is not going to have a BR match category for these types of guns so I need to go to Scheutzen matches to shoot this gun. There are two per summer in our area that I try to make every year. On the seating depth detail, this gun likes the bullet just barely contacting the rifling, either greasers or paper patch bullets. One variable with these types of guns is how much do you compress the powder? Each Fg grade of powder likes a different amount of compression. 

No shooting here for a while and its not due to lack of primers. The day time high temperatures are often predicted to be either positive or negative single digits…..without the wind!

Tom

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R. Dupraz posted this 3 weeks ago

Don't know anything about the handgun long range steel but when I was shooting the long range BPCR steel matches, me and my buddy would show up the day before or at first light on match day to get sight settings for all the targets. And then enter them in our super-secret data books for the match.  Then we had the data for the next year and all we had to do was to verify and maybe fine tune.

When I started paper patching my Shiloh 45x 2.4, I quit worrying about OAL and whether the bullet touched the leade or not because I patched to bore. With some experimenting, I found a charge of Goex fff that the rifle liked and then bult the wad column such that I could shove that 550 grain missil as far up the bore as possible and still be held in the mouth of the case without falling out when the case was held upside down. Usually only about 1/4 " of the bullet was in  the case after thumb seating. 

During that time I bought Goex by the case so the lot would be the same. Any new lots, new load developed. 

 

 

Ten shots, 185 yds. Shiloh 74 Sharps.45 x 2.4   Paper patched to bore, 85 grains of Goex FFF off of sticks prone   

 

 Iron sights

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Tom Acheson posted this 3 weeks ago

Good info on the Sharps loads, thanks!

My 418-grain Brooks mold is a dual diameter design and I patch to 0.410” but not to bore. Maybe I should look into that. I wrap the bullet and then pass it through a .410 CB sizing die, just to tighten up the dry patch. 
I can recall various forum posts (elsewhere) that described the base of the bullet being in the case only 1/10th to 1/4 inch. Included were several veggie or poly wads to get the desired relationship between bullet and chamber contact.

The round is a .40 cal. 2 1/2 or .40-70 Sharps Straight. I was given “permission” to buy a case of powder a month before I retired. All of my local load development shooting is done at 200-meters. I do need to get out to shoot and load test more!

Tom

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R. Dupraz posted this 3 weeks ago

Well, I have breach seated for a 32-40 and a 38-55. Both dedicatedt target single shot rifles and they both would dang near poke those castings down the same hole at 100. So this feeble mind reasoned that the closer that I could get to that method with my 45 x2,4 the better it would shoot. 

1. That 550 grainer is automatically aligned with the axis of the bore perfectly every time. forget about concentricity and all that.

2.  Eliminates agonizing over seating depth and OAL

3,  As well as making neck tension a thing of the past

It had a noticeable positive effect on the accuracy of the 45 x 2.4. Those PP 550 grainers will outshoot the GG most every Time. 

when the shooter is paying attention.

 

R

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gnoahhh posted this 3 weeks ago

Indeed. It's why I cut to the chase in ASSRA competition and breech seat for my .32-40's, both High Walls, one of which is a Pope. Going to take it a step further this year and start using the false muzzle on the Pope and muzzle load. Alignment in the throat/leade is guaranteed, and chasing that kind of alignment with fixed ammo is a challenge.

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OU812 posted this 3 weeks ago

Fitting is a challenge. You can spend more time thinking and fitting than shooting.

Here is a pound cast of a 300 Whisper chamber (free bore length .190", freebore diameter .309, bore diameter .300, 8 groove rifling) Thompson Contender Pistol 14" barrel.

Bullet is compressed top to bottom in special cut die to slip fit dimensions. My guess is bullet will shoot well because of good fit, but different bullet length may be required for best accuracy

 

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Wm Cook posted this 3 weeks ago

OU is that a 31-220F or G from Accurate? And if it’s a tapered nose what does the front & rear measure?

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OU812 posted this 3 weeks ago

The bullet i designed (Accurate 31-210M) is cast undersize then "compressed" to larger diameter to make fit any factory 30 caliber chamber. Bullet is not swaged to make smaller, but compressed or bumped to make larger any diameter you need.

Pistols are too hard to shoot accurately. I really want a Remington 700 chambered in 300 Blackout

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OU812 posted this 3 weeks ago

That bore ride bullet in picture is non tapered and after bumping measures .300 @ bore ride section, bands measure .309. Accurate Moulds shows bullet specs larger than I requested. My mould cast smaller diameter than shown in diagram. .298 bore ride section, .310 @ bands. I do size and installl gas check before bumping. 

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Geargnasher posted this 3 weeks ago

"Larry's post above, by using a scientific approach to find the truth about an aspect of CB shooting, discredits a perfectly reasonable sounding theory about pressure rise. These things can be done -- we just don't generally do them, and when they are done we tend to disregard the results and go back to our previous belief."

NO. NO. NO.

When are you going to learn? One man makes one statement and you take it to the bank forever, just like with neck tension.

Here's what you DON'T know about any pressure measurment taken with a strain gauge: it doesn't register pressure until it is enough to begin stretching the barrel steel. Oehler suggests a 7,000 P.S.I. offset to account for this. Even jacketed bullets only require 3-5,000 pounds of pressure to engrave according to Noconos, cast bullets considerably less. So there is no way a strain gauge could tell the difference. The pressure curve will be advanced very slightly and peak pressure increased a few hundred to a couple thousand pounds by a hard jam into the lands, this has been well documented by ballisticians throughout history. 5.56x45 NATO fired in a .223 winchester chamber, anyone?

But the most important thing that jamming or jumping a cast bullet does happens to the bullet itself. When you start pulling lead rings out of your chamber with a brush because you were riveting the alloy and they go away when you either a.) Back off the charge, b.) Toughen the alloy, or c.) Back off the ball seat .030", you start to do some thinking about the dynamics if what's going on. Veral Smith and Mann both did some interesting short-barrel experiments that shows us when and how the "bubblegum" effect happens. Examination of bullets recovered from a soft media trap will also tell you volumes that a strain gauge will not.

What we have to overcome is myopia and false conclusions, not lack of data.

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Larry Gibson posted this 3 weeks ago

Yes, it is true there is an “offset” with strain gauge measurements.  There is also an offset with every other type of pressure measurement systems for measuring chambering pressure.  Those offsets account for the pressure required to expand the case, to register any measurement on any device.  Why?  Because we do not measure the pressure directly.  There is no measurement system that measures inside the cartridge.  We measure the pressure through secondary means just as we do many other things, the speedometer on your vehicle for instance. 

As I stated previously, A cast bullet, even a "hard" cast bullet, is much softer than a jacketed bullet.  The pressure needed to swage down and engrave the lands into the bullet is much less.  That swaging down and land engraving happens very early, at the beginning, of the pressure rise.  It seemingly, so far at least, has little if any measurable effect in the pressure or pressure curve with normally sized cast bullets that are not larger than the chambers throat.

If there was a measurable increase in pressure it would manifest itself in the rise to peak pressure or the time/pressure curve (trace) and the time in milliseconds of that rise to peak pressure.  So far, again as previously stated, there has been no indication of that with cast bullets when seated off the leade or into the leade.  However, gearnasher states; “The pressure curve will be advanced very slightly and peak pressure increased a few hundred to a couple thousand pounds by a hard jam into the lands,”.  There is no indication in all of my pressure measurements (thousands of different test loads of multiple cartridges) that such occurs.  It did not occur when specifically tested for such. 

Now to give gearnasher his due, it is well documented that a pressure increase can very well occur with jacketed bullets because a jacketed bullet does, in fact, require considerably mor pressure to engrave into the rifling than does any cast bullet.  That has, indeed, been demonstrated, tested and measured by many ballisticians.  I have measured that effect on pressure also. 

Gearnasher’s statement of “this has been well documented by ballisticians throughout history. 5.56x45 NATO fired in a .223 winchester chamber, anyone? Is misleading at best and incorrect at face value.  There is no 223 winchester.  I’ll assume he meant 223 Remington(?) to correct the incorrect part. 

Where his statement is misleading is the half truth.  One can shoot all the M193 equivalent military ammunition in .223 Remington chambers with no adverse increase in chamber pressure from firing in that chamber.  M193 will probably give a higher pressure simply because it was loaded to give that higher pressure.   That has “been well documented by ballisticians throughout history”, at least throughout the history of the 223/5.56 cartridge.  However, if one fire SS109 or M855 (Green Tip) in a standard SAAMI spec 223 Remington chamber the bullet may jam into the leade and a subsequent increase in the intended chamber pressure can result.  It does not always occur but sometimes it does.  The Army’s manual states one can fire M855 in older M16A1 chambers, with the only adverse effect being a lack of accuracy due to the 12” twist barrel.  No increase in pressure just poor or non existent accuracy. 

My conclusion of, ‘It seemingly, so far at least, has little if any measurable effect in the pressure or pressure curve with normally sized cast bullets that are not larger than the chambers throat. Is neither myopic nor false.  My conclusion is based on factual testing, not internet suppositions.  

LMG

Concealment is not cover.........

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freebullet posted this 3 weeks ago

There is most certainly a 223 Winchester. Had a Browning bolt in 223 win, had an offical designation of 223 wssm. It was a barn burner cartridge and often referred to as 223 win.

Heat treated ww bullets can exceed a bhn of 30. Copper toughened alloys can well exceed that. Copper jackets can range 30-40 bhn. Just because one mans limited testing doesn't show a known conclusion doesn't mean it's all inclusive to include testing that has gone further in depth in testing the limitations of cast bullets in use.

Some folks test & exceed traditional cast limitations. The info isn't to hard to find or replicate in your own tests.

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Wm Cook posted this 3 weeks ago

Gearnasher and Larry laid out two positions and anyone following this thread can choose what path to follow.

But their positions go to the heart about what the original OP asked regarding jump or jam. Accompanied with the light nudge from OU812 when he asked “Shouldn't we be talking about more perfect bullet fit and alignment. ”

Larry did not say jamming helps or hurts accuracy. He just passed on his testing experience that pressure should not be a problem. I believe all of us would agree if you had a super hard alloy or jacketed bullet jammed in the lands pressure would spike. All of us have blown primers with jacketed bullets.

But unless we are using hard hard bullets at high velocities I’m comfortable there should be no issues.

Case in point. The bhn I shoot is in the 18 to 22 range with a 30 cal bullet running around 1750. My freebore measures .3084. My driving bands will always seat against the wall of the freebore entrance and the bullet will be swaged down to the free bore dimensions and I have never seen pressure signs.

Getting to what OU812 said about fitting. Since I’m using neck sized fire formed turned brass, kissing or jamming the driving bands and if it’s a taper design I could in theory have Bullet control at three locations.

That’s provided I guessed right about the nose diameter (front to rear) fit of the tapered nose design in my free bore/leade that I ordered from Accurate.

Lot of thing could be organized to test out how jump, jam or self seat affects accuracy. But much of those results would be BS (barrel specific). Bill

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Wm Cook posted this 3 weeks ago

Gonna have to clean up that acronym for “barrel specific”. Also need one for “shooter specific”.

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Larry Gibson posted this 3 weeks ago

freebullet

"There is most certainly a 223 Winchester. Had a Browning bolt in 223 win, had an offical designation of 223 wssm. It was a barn burner cartridge and often referred to as 223 win."

We can have local colloquial names for anything.  Perhaps that is what you call it in your neck of the woods.  Problem is the real name is 223 Winchester Short Magnum or 223 WSM.  It is not one anyone would or should shoot or attempt to shoot a 5.56 in.  If gearnasher meant that cartridge, as you suggest, then he was even more incorrect.  However, I do not believe the 223 WSM was the cartridge he was referring to.  Additionally, the is no "proven" evidence of the use of a 5.56 cartridge in a WSM chamber the point of which using a 5.56 in a 223 chamber.

BTW; mild, soft copper/zinc alloys (95% Cu/5.0 % Zn) have a BHN of 114.  Harder jacketed bullets only have BHNs that are higher.

LMG

Concealment is not cover.........

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MP1886 posted this 3 weeks ago

Yes, it is true there is an “offset” with strain gauge measurements.  There is also an offset with every other type of pressure measurement systems for measuring chambering pressure.  Those offsets account for the pressure required to expand the case, to register any measurement on any device.  Why?  Because we do not measure the pressure directly.  There is no measurement system that measures inside the cartridge.  We measure the pressure through secondary means just as we do many other things, the speedometer on your vehicle for instance. 

As I stated previously, A cast bullet, even a "hard" cast bullet, is much softer than a jacketed bullet.  The pressure needed to swage down and engrave the lands into the bullet is much less.  That swaging down and land engraving happens very early, at the beginning, of the pressure rise.  It seemingly, so far at least, has little if any measurable effect in the pressure or pressure curve with normally sized cast bullets that are not larger than the chambers throat.

If there was a measurable increase in pressure it would manifest itself in the rise to peak pressure or the time/pressure curve (trace) and the time in milliseconds of that rise to peak pressure.  So far, again as previously stated, there has been no indication of that with cast bullets when seated off the leade or into the leade.  However, gearnasher states; “The pressure curve will be advanced very slightly and peak pressure increased a few hundred to a couple thousand pounds by a hard jam into the lands,”.  There is no indication in all of my pressure measurements (thousands of different test loads of multiple cartridges) that such occurs.  It did not occur when specifically tested for such. 

Now to give gearnasher his due, it is well documented that a pressure increase can very well occur with jacketed bullets because a jacketed bullet does, in fact, require considerably mor pressure to engrave into the rifling than does any cast bullet.  That has, indeed, been demonstrated, tested and measured by many ballisticians.  I have measured that effect on pressure also. 

Gearnasher’s statement of “this has been well documented by ballisticians throughout history. 5.56x45 NATO fired in a .223 winchester chamber, anyone? Is misleading at best and incorrect at face value.  There is no 223 winchester.  I’ll assume he meant 223 Remington(?) to correct the incorrect part. 

Where his statement is misleading is the half truth.  One can shoot all the M193 equivalent military ammunition in .223 Remington chambers with no adverse increase in chamber pressure from firing in that chamber.  M193 will probably give a higher pressure simply because it was loaded to give that higher pressure.   That has “been well documented by ballisticians throughout history”, at least throughout the history of the 223/5.56 cartridge.  However, if one fire SS109 or M855 (Green Tip) in a standard SAAMI spec 223 Remington chamber the bullet may jam into the leade and a subsequent increase in the intended chamber pressure can result.  It does not always occur but sometimes it does.  The Army’s manual states one can fire M855 in older M16A1 chambers, with the only adverse effect being a lack of accuracy due to the 12” twist barrel.  No increase in pressure just poor or non existent accuracy. 

My conclusion of, ‘It seemingly, so far at least, has little if any measurable effect in the pressure or pressure curve with normally sized cast bullets that are not larger than the chambers throat. Is neither myopic nor false.  My conclusion is based on factual testing, not internet suppositions.  

LMG

 

Larry  you are incorrect about your pressure statement for inside the cartridge.  I believe this picture is self explanatory.

 

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MP1886 posted this 3 weeks ago

Bill,

 "Some may think that casting quality competition bullets is an art.  But maybe we aren't giving enough credit to the individual that worked in the field long enough that skills were gained (trained or self taught) that enabled them to exceed."

That is the definition of a manual art. 

Science is "knowledge about the natural world that is based on facts learned through experiments and observation." It has to be 100% repeatable by anyone doing the same experiments without regard to place or time. Cast bullet shooting isn't there yet.  

IMHO, Ric 

 

You said in your honest opinion so I can accept that.  Cast shooting with 100% repeatability has been achieved by some, but there would be many who bombard them with ridiculous tests to guarantee they would fail. That's why many who can do it won't tell everyone. There are also many that you can coach through a 100% repeatable experiment every step of the way and they still will fail and no be able to repeat it.  

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MP1886 posted this 3 weeks ago

One can shoot a jacketed bullet load with the bullet jammed into the rifling IF he builds up to that load! Many do load that way or at least with the jacketed bullet touching the leade. Then on the other end of the field there is Weatherby, for an example, with it's really long freebore. The bullet is up to pretty good velocity when it hits that bore and rfling. Wonder how that looks on a pressure tester. Comments Larry?

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Wm Cook posted this 3 weeks ago

MP1886, Ric, OU812, Ken, Larry and gearnasher:

There are also many that you can coach through a 100% repeatable experiment every step of the way and they still will fail and no be able to repeat it. 

Agreed: 

Regarding cast accuracy 

  • Accuracy requires you to do the same thing the same way every time.  This includes the learned skills of hand loading, bench discipline, components used, casting and equipment selection. 
  • Not everyone has the ability to understand this and/or they feel no sense of urgency to put in the time to get it right.  That doesn't make them right or wrong, its just that they choose accept results that differ from mine.  For some its a passing fad and when they find out how much time it takes to learn how to shoot cast accurately they drift away.  For for the shooter that comes into it with an open mind and can follow directions it's a learnable manual art which is how I think Ric described it.  My point was it isn't magic.  The term bubble gum makes me cringe.  Chuck Duncan agg'd .538 in the 5 shot 100/200 yards at the NT this year. That was with Linotype and 1750fps.  I think that's pretty good.  And yes I understand that the NT is not the end all to cast accuracy and that many shoot outside of competition and can do just as well.  But these are public record numbers.
  • There is a sense of frustration teaching firearm accuracy when the person you are working with wonders off thinking they already have it figured it out.  Or if the situation is reversed and the trainer has blind spots or biases that are flawed.  How many times have you heard comments about myths or old habits that although have proven to be defending a weak position, they are still passed on as fact.  As a good student to you have to take what you learn to the range and verify what you were taught.
  • There are times that digging to the N-Th degree is important.  And my deeply respect those that go to this level.  However I am not a ballistics expert. 

Although I am on the left side of the learning curve on cast accuracy, I have 30 years of jacketed accuracy that has given me the ability to see some readily available high value paths to cast accuracy improvement. 

I was fortunate to pick up a mentor from the forum this year who has given me an in-ordainment amount of solid advice.  When I turned to cast accuracy this year I brought with me benchrest level hand loading skills, bench discipline, and solid equipment selection.  But after melting alloy for 30 years I can now say that for the first time in my life I understand how to cast quality bullets. I want to thank my mentor for that.

A lot of us new to shooting cast accuracy appreciate those individuals that take a chance and pass on the basics.  But I can sadly say that I fully understand the apprehension of getting burned with a bad experience.  

The next few months is going to show whether I've got a handle on bullet to throat fit.

Its going to be a good year. 

Bill C.

 

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John Alexander posted this 3 weeks ago

Gearnasher had this to say four days ago: "I say all that to recommend never sizing larger than throat entrance diameter, never jamming a cast bullet hard into the ball seat, never use hard, brittle alloys, and avoiding perfectly-matching bullet/throat angles which bring a sudden increase to engraving resistance and spike the powder pressure against the bullet's base. I know this is contrary to everything ever done in cast benchrest shooting, but it works very well in conventional, production rifles." 

I have been wondering what ought to be said in response since the statement shouldn't stand as some set of iron clad rules passed down from on high without experimental results to confirm. 

 Except for "never sizing larger than throat entrance diameter", most of the things warned against above are exactly what most winners in CBA matches do. Most shooters find it helpful to "jam" their bullets in one way or another to prevent early hot gases from rushing past and eroding the bullet and changing bore condition and possibly leading the bore. Hardness is a relative term but in CB shooting linotype is considered both hard and brittle, yet virtually all the shooters in heavy, UNP, and UNR classes and most of the other shooters in other classes, with the exception of breech seaters, use linotype. Since John Ardito started doing it over forty years ago, most of the winners in heavy, UNP and UNR have used a bullet swaging die and a throat cut with the same reamer for a perfectly-matching bullet/throat. This is not to say that CBA shooters have it all figured out. But the closest thing we have to evidence of what works for cast bullets is the results of public matches where there are no do-overs and the results are judged by independent judges. 

There may be a tiny unmeasurable "spike" caused by jamming cast bullets -- or not. You can reason yourself into the notion that there might be one, just as Aristotle reasoned himself to the conclusion that women had fewer teeth than men without looking in his wife's mouth. But until we have evidence, not only of its existence but that it is big enough to affect anything measurable, we have other things to worry about.

For polymer coated bullets with their melt resistant coating things may be completely different.

John

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freebullet posted this 3 weeks ago

Larry "as you suggest"

I'm not claiming what another meant, he can speak for himself. There is a 223 winchester is what I said.

Most bullet jackets do not measure much above 40bhn. You insinuate because lead is soft there couldn't be a pressure spike when in reality hardness or toughness is all over the map with both base alloys.

If all fit issues are perfected jamming bullets isn't genrally required. It can & sometimes does help overcome minor fit/alignment issues. Think I'm bouncing back offline here. Good luck fellas.

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Larry Gibson posted this 2 weeks ago

freebullet

Not sure where you are getting your information on the BHN of bullet jackets but if you check with metal suppliers, you'll find the BHN of pure copper to be 80 - 85 BHN and the softer brass alloy used in bullet jackets to be 114 +/-.

 

Also, I did not "insinuate" anything.  I stated a fact.  That fact was that in the testing of thousands of cast bullet loads in rifle cartridges I had not observed any such increase in the peak pressure nor rise to that pressure with cast bullets seated into, on or off the leade. 

My observation at the end of that 1st post was "It seemingly, so far at least, has little if any measurable effect in the pressure or pressure curve with normally sized cast bullets that are not larger than the chambers throat."  In effect, it was found through actual measurement of the pressure there was no measurable effect.

We have found the last 20+ years with the availability of more precise pressure measuring equipment to better understand what is actually occurring during the internal ballistic phase.  That has overturned many theories espoused by many "experts" of days gone by.  Unfortunately, with the advent of internet those theories still abound and are continually proffered.  That is very unfortunate because we cannot learn and advance the study and use of cast bullets if we do not accept actual proof, even though it may contradict those past theories no matter how reasonable they may sound.

To paraphrase a too much over used phrase these days; "follow the science" not the theory.

LMG

Concealment is not cover.........

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Geargnasher posted this 2 weeks ago

"I have been wondering what ought to be said in response since the statement shouldn't stand as some set of iron clad rules passed down from on high without experimental results to confirm. "

Hey John, my target should speak for itself, which was the context within which my statement was made.

Why don't you ask Larry Gibson what the target looked like when he tries to shoot ten of any cast bullet, much less a 162-grain one, through a military Swedish Mauser at nearly 2500 feet per second in under three minutes?

You guys can open your eyes, or continue to be completely arrogant an myopic and get what you always got. I'm done trying to help you THINK anymore.

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MP1886 posted this 2 weeks ago

Larry, You often say "we".  Makes it sound like you work at a company dealing in these matters.  So what do you mean?

Also no comment on nothing measures the pressure inside the cartridge huh?  If you're going to say things, that you infere you're 100% right, you had better back them up with believeable statements and proof. 

I too would like to see your 10 shot target with the 6.5 Swede such as geargnasher suggested. 

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Larry Gibson posted this 2 weeks ago

MP1886

By “we” I meant those of us (or some of us if you will), whether industry or individuals, who study ballistics and conduct actual tests using scientific methods which are proven.  I.e., those of us who prefer to prove or demonstrate through scientific testing instead of continued pontification and theorizing. 

 FYI, in the 15+ years I have been conducting pressure tests I have tested thousands of different loads in different cartridge.  I have conducted tests commercially [meaning I was requested to do the tests and got compensated for doing so] for powder manufacturers and importers, commercial cast bullet makers, commercial reloaders and ammunition manufacturers.  I have also conducted numerous tests at the behest of members of this forum and another forum.  Additionally, I have conducted a lot of pressure testing of my own loads amounting to thousands of rounds pressure tested.  None the less I am always open to learning, if you have more experience measuring pressures please advise?

If you are “going to infer” there is a method to directly measure the pressure inside a cartridge when it is fired, please advise of what that method is?  I know of no such method; thus, I stated a fact and did not “infer” anything.  So perhaps you can “had better back up” your own inference?

Well, as to gearnasher’s comment to John; “Why don't you ask Larry Gibson what the target looked like when he tries to shoot ten of any cast bullet, much less a 162-grain one, through a military Swedish Mauser at nearly 2500 feet per second in under three minutes?  I have previewed the thread over on Artful Forum where he posted that picture of his group.  Several there, including gearnasher, are still too wrapped around the axle apparently trying to disprove the RPM Theory wrong.  As I said over and over ad nauseum, the RPM Threshold of 120,000 to 140,000 RPM applies to regular lubed cast bullets of ternary alloy.  Note that gearnasher is using a PC’d cast bullet.  That, in and of itself, ups the RPM Threshold.  All bullets, regular cast, PC’d, PP’d or jacketed will have an RPM threshold.  It just may not be reachable within the pressure/velocity restraints of the cartridge it is used in.  Also, the RPM Threshold does not impose a “limit” as they continue to say on the Artful forum but can be moved up or down, just as I’ve continually said and, perhaps, as gearnasher has demonstrated with the use of PC'd bullets(?). 

Thus, I do not have any pictures of any groups regardless of the velocity with PC’d cast bullets simply because I have not got into PCing yet.  It would be nice it gearnasher could repeat that group size at 100 yards and then also at 200 yards to see if group expansion expansion at 200 yards was linear in size to the 100 yard group.  In my own HV 6.5 Swede testing I did manage to hold several 10 shot groups less than 1.5 moa at 100 yards with the regular cast and lubed 129 gr Kurtz bullet.  The velocity was only 2080 fps but subsequent 200 yard groups ran 2 ¾ to 3 moa.  That was non-linear group expansion and thus the load had exceeded the RPM threshold.

Now I have to ask, just what the heck does this discussion about gearnasher’s group he shot with the 6.5 Swede using PC’d bullets have to do with cast bullets seated off, next to or bumped into the leade?  Perhaps you or gearnasher could explain your motives for the thread drift?

 LMG

Concealment is not cover.........

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OU812 posted this 2 weeks ago

The person with the condition usually isn't aware of his or her behavior.

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MP1886 posted this 2 weeks ago

I know it's hard for you to admit you're wrong Larry.  I posted a picture of just ONE method of pressure testing the inside pressure of a cartridge.  There are plenty more. I'm sure, well maybe I'm not, that you are aware that copper crusher is contoured to the case wall up as near the shoulder it can be placed. The wall is very thin at that point. So being the copper crusher and the wall are nuts to butts just how much pressure do you think it takes to transfer through that wall to the crusher? Not very much for sure. 

So you did pressure testing commercially for all the industries you mentioned.  I'll ask Allan Jones if he knows you and if you helped him. We all, or most of us, know who Allan Jones is. 

Geargnasher asked you to shoot ten shot groups at 2500 fps from the Swede, he did not bring up the rpm thingy, YOU DID!

Go back to your computor, your reply failed to resolve anything. 

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MP1886 posted this 2 weeks ago

On this next diagram Larry, unless I have a reading comprehension problem, I believe they say they drilled a hole through the wall of the case on a live cartridge. Gosh, wouldn't that measure the internal pressure? Remember gas pressure pushes all around in all directions evenly.   Come Larry admit you weren't aware of this, I won't hold it against you. 

 

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Larry Gibson posted this 2 weeks ago

Well aware of both systems.  You need to take a closer look at the CUP method drawing.  There is a GC and piston between the case and the copper "crusher".  When the cartridge is fired the gas goes through a predrilled hole in the case.  The gas check seals the gas and drives the piston to crush the copper pellet.  The crushed copper pellet is then measured to determine the amount of "crush" in inches. That amount of crush is then found on a table that comes with the copper pellets which converts the amount of crush to psi..  The amount of crush listed on the table then tells the amount of "psi" supposedly needed to crush the pellet that much.  That is a secondary measurement as the system gives no direct measurement of pressure.  None of the apparatus of the CUP method measures the psi inside the case.  The CUP system can only measure the peak pressure and cannot provide a time/pressure curve or trace.

Basically, the same with the transducer system.  A hole is drilled through the chamber and a small rod rests against the case.  When the cartridge is fired the rod pushes against a piezo which generates a current.  The amount of current is input into a computer program which converts it to psi.  Again, no direct measurement of the psi on the inside of the case as none of the transducer is inside the case.  The transducer can provide a time pressure curve of the rise to peak pressure and decline of pressure until muzzle exit.  Of course, there is the "offset" previously mentioned as the pressure to expand the case and pressure to push the rid compressing the piezo must be input into the data.  

 

Be nice to get back to the topic, eh?

LMG

Concealment is not cover.........

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MP1886 posted this 2 weeks ago

Explain away the one with the hole in the case, you can't.  We get back to topic when you admit you errored. 

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JeffinNZ posted this 2 weeks ago

If you people can't play nicely I will lock this thread!!!!

Don't make me stop this car!

Cheers from New Zealand

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Shopdog posted this 2 weeks ago

Skipping all the "he said,she said"

90+% of my accuracy work is with bore riders. And I have some varmint rigs that will give the jacked bullet shooters some serious competition. Higher velocity "can" be the key that unlocks that next door to accuracy. Several of my rigs won't bughole until velocity is WELL into JB "book" loads BTW.

So,new to me rig would've already seen me plotting/planning before hitting the loading bench,if you know what I mean. Rarely do I load for "pure accuracy" as I'm a varmint killer. So the calcs can be off a bit.

Assuming a bore ride nose;

Actual chamber neck diameter is the start. Then figure out how you're going to dial in bullet diameter considering case neck thickness.... turn?no turn? Now think about how you're going to compare different neck tension. This is where hunting vs target work can trip you up. 10 shot groups may be a metric in target world but means little in the gaming fields..... we get NO foulers. And your scope dialing better be well sorted.

Get a good handle on the above. Now comes the nose tapering.

You can make a nose tapering die pretty durn easy(contact me if you need help). Where you stop the taper on the nose is your tuning, "ace up the sleeve". It allows you to change the bullet base "height" within the loaded cartridge. Use it as a fine tune.....

So in sorta answering the OP,ain't any real bias for me. Get the "numbers" right on the diameter(as posted above),get in the ballpark for the powder weight(pre planned). Try a cpl neck tensions,(.002, and .004 side by side comparison).

Then,play with that location on the nose where the taper stops. Easy peasy Japaneasy.

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Ken Campbell Iowa posted this 2 weeks ago

thanks Shopdog ... some good thinkin-seeds ...

especially your comments on playing with the tapers ... i think you refer to the melding of the groove diameter to nose diameter ...

especially since i have recently been grinding reamers to various degrees to do just that in bullet squisher dies  ......  

guess that will sorta allow changing the ratio of bore-rider nose to body groove diameters ..

i have always thought that bore riders are a good way to get down to about 1 moa, but full groove diameters necessary to get much under that ...  probably from my 22 rimfire days, where 50 rifles show up and all shoot 5/8 moa MAX from store-bought ammo ...  50 shots under a half inch at 50 yards ... is there anything to learn there ??  .... heh ...

looking forward to any more thoughts you might have on this, and targets would be nice just to tease us ...

thanks again, ken 

 

 

 

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OU812 posted this 2 weeks ago

Ken i agree 100% with what you just said. Taper bumping is the easiest way. Bullet should also be squeezed top to bottom for best results. It really helps if you have a lathe large enough to experiment more.

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ray h posted this 2 weeks ago

OU812, please explain the 3 reamers above the chamber reamer. I assume they are throating reamer  but looking different than the 2  I own. I'm guessing the length of the reamer section is dependent on reamer angle?? Does that shoulder behind the reamer section align on the chambers shoulder??? I think the short tubes above are various dia pilots. Seeing the tools sure helps someone like me that's trying to learn put a face to terms everyone talks about.

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OU812 posted this 2 weeks ago

I dabbled in throating a short chambered 308 Win Shillen barrel using a PTG .310 diameter 1.5 degree included (.75 per side). I used the correct diameter pilot and cut throat by hand. I also taper cut the blank PTG 30 cal die. Crude method I know, but the 308 shot really well after taper bumping.

The chamber shaped piece on cutter acts as a stop mostly, but also used it to align cutter before cutting. Their are better methods, such as using a lathe.

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OU812 posted this 2 weeks ago

The reamers top to bottom are:

.310 steep factory angle throater

.310 1.5 included angle

.309 1.0 included angle

308 Winchester reamer

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Larry Gibson posted this 2 weeks ago

I guess I am a crusher/jammer as over the years I've come to believe seating the drive band or ogive slightly into the leade (ball seat by some definitions) is more accurate.  However, I've no real empirical data proving accuracy is better.  As I went to the range yesterday to pressure test some 35 Rem loads in my M91 Mauser I like to take another rifle along to shoot while waiting for the test rifle barrel to cool between tests.  Thus, I took the M70 target .308W along with a few of the 30 XCB target loads for it.  

The M70 is a stock PF stainless that shot 1/2 moa with 175 MKs over Varget back when I was shooting 600 - 1000 yard belly matches.  It has about 2500 such jacketed rounds through it.  I only use it for cast bullets these days though occasionally (pre COVD anyway) getting over to Phoenix for a CBA match.  I use the weight sorted 30 XCB cast of #2 alloy, WQ'd, Hornady GCs sized at .311 (they drop at .3105) the sized .310 in a honed out Lee sizer.  They are loaded to a "crush" fit oal over 16.5 gr of 2400 (no filler) in LC Match cases with the flash holes drilled out and fully match prepped.  The cases are fire formed and neck sized in a Redding NS dies with a Lyman 31 M die used to expand the neck to .002 neck tension and flare the case mouth.  The velocity runs 1788 fps with the SDs (10 shots) running 5 fps +/- and the ES running under 20 fps.

I use the "SAAMI Twist" method of putting the loaded round into the rifle.

I had not shot the M70 for some time which was previous to my cataract surgery.  Thus, I needed to adjust the scope so the vertical crosshair of the Leupold 6.5x20 target scope was vertical and had to refocus the ocular lens.  I figured both would slightly affect the zero slightly and it did.  I put 4 CBA score bulls up at 100 yards.  I the fired 6 shots on the "SS" bull (bottom left) after putting 2 shots into the berm to foul the bore.  1st three shots were low right, so I adjusted up 3 click and the next two shots cut each other slightly high right.  I went down one click and left one click and put the 6th shot into the 10 ring.   Went back to the test rifle for another test string.

Came back to the M70 and shot the 5 shot group on the upper left target.  The nine o'clock 10 is the first shot from the cold bore.  I always fire a fouler before shooting a string for score in CBA matches as that first shot is usually slightly out of the group, as we see.  Went back to the test rifle letting the M70 "cool".

I then shot the five shot group on the upper right target. the first shot is the low ten, again just slightly out of the group.  Back to the test rifle letting the M70 cool again.

Next i shot a 5 shot group on the lower right target.  Those five are the five center shots over the ten ring with the first cold bore shot being the low nine.  Back to the test rifle giving the M70 a cool down.  

When I came back to shoot the last five shots a steady 2-3 MPH wind had started coming from 3-4 o'clock.  I did not hold for the wind as i wanted to see how much wind drift there would be.  The first cold bore shot is the nine out at nine o'clock with the other four cutting the slanted hole on the edge of the 10 ring at 9 o'clock.  My past experience with such a wind is to hold on the 10 ring at 3 o'clock.  That would have been perfect this time also.

Average group size for the 4 five shot groups was .823"  Was a good day testing the 35 Rem and shooting the M70.

 

Concealment is not cover.........

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Squid Boy posted this 2 weeks ago

Larry, you mention the "SAAMI Twist Method" of loading a rifle above but I have never heard nor read of this technique in any SAAMI resource I have nor anything on their website. Perhaps it is officially called something else since a search of their site comes up empty. Can you elaborate? Squid Boy

"Squid Pro Quo"

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Larry Gibson posted this 2 weeks ago

The SAAMI Twist is a variation of the test fixture loading procedure.  The procedure is described in the manual.  Of course using a standard firearm, the load procedure is modified slightly.  I picked up the terminology from Dr. Oehler some years back.  I use the modified SAAMI method he taught me.  

Sitting at the bench with the rifle, action open, on bags I have the ammunition in a loading block or a 50/100 round MTM ammo box with the bullet up sitting on the bench to the right.  With the right hand trigger finger and thumb a case is removed from the box keeping the bullet up.  It is tapped lightly on the bench then twisted back and forth a couple times with the finger and thumb.  That is the SAAMI part and the 'twist".  The variation is next as the case is inserted into the action case with the rim/head against the bolt while keeping the bullet up at an angle forward.  The amount of clearance in the action opening and scope dictates the angle.  The cartridge is gently placed on the follower.  The bolt is then slowly closed. 

The "SAAMI Twist" simply keeps the powder, especially in low density loads, to the rear of the case.

LMG

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RicinYakima posted this 2 weeks ago

Fed my Springfields with that technique for 25 years, but used the right lug raceway,  works well to reduce ES, but don't know if reduced group size. 

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Squid Boy posted this 2 weeks ago

This is the excerpt from the SAAMI Procedures for Center Fire Rifles Section II

IV.HANDLING OF AMMUNITION

A. Cartridges to be tested should be placed in a vertical position with primer-end down in a recessed holding block.

B. When the appropriate test barrel has been properly serviced and the chronograph reset, a cartridge should be lifted vertically from the block. It should be rotated slowly, end over end, in a vertical plane through 360° pausing momentarily when the powder is at the bullet end and again when the powder is at the primer end.

C. The cartridge is then rotated slowly, a minimum amount to enter the chamber, keeping the primer end in the lowest possible position until inserted gently and carefully into the chamber.

D. The cartridge should be seated in the chamber as far as practicable with the fingers. The bolt or breech mechanism should be closed gently in order not to disturb the position of the powder in the cartridge case. The object of this method of handling cartridges is to position the propellant powder at the primer end of the cartridge case by permitting it to fall gently against the primer while rotating the case.

E. The rate of fire should not be rapid enough to cause excessive heating of the barrel. The time between rounds depends on the equipment, as the barrel may be cooled by a constant stream of air on the outside or by directing air through the bore after each ten rounds.

F. Ammunition conditioning should be between 60° - 80°F (15.6° - 26.7°C). G. A minimum of one and up to three warming shots should be fired before firing each series for record. The velocity and/or pressure of these shots may be recorded, but should not be included in the record of the sample.

I don't see any connection between the procedure you mention as a collaboration between you and Dr. Oehler and the SAAMI procedure outlined above. In the SAAMI procedure the case is turned end over end and then inserted in such a way as to keep the powder at the rear of the case. There is no tapping or twisting as you describe. It seems to me that "SAAMI Twist" is not altogether an appropriate name for your procedure and is misleading to a certain extent. Both procedures do allow for the powder to remain at the base of the case but beyond that they differ significantly.

Squid Boy

 

 

"Squid Pro Quo"

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Larry Gibson posted this 2 weeks ago

Squid Boy

Perhaps you should re-read my answer to you.  I said what I used was a "variation" and the procedure was modified for a standard action firearm.  The above from the SAAMI manual is for the use of a Universal receiver.  You might pull out your Webster's dictionary, if you have one, where in the definition of "twist" you will find it means "a variant approach or method".  

BTW, I did not 'collaborate" on the term with Dr. Oehler.  I said I "picked up the terminology" from him, considerably different than "collaborate".  The terminology refers to a variation of the specific procedure used when testing is done with a regular firearm from a shooting bench.  Universal receivers are not fired from a normal shooting bench and there is no action as such or scope to interfere with loading the cartridge straight into the chamber from the rear of the receiver.  

Bottom line, so maybe you can "see it" is the "twist" is a variation of the SAAMI procedure to fit the low load density load and the type of action used.   My apologies if I did not make that clear.

LMG

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Squid Boy posted this 2 weeks ago

Sorry but I took that "he taught you" as more than just a sharing of terminology. I don't believe that you meant twist in the way that Webster defines one of the possibilities for the word. Perhaps you should call it the Gibson twist or the Gibson / Oehler twist and reduce the possibility for misunderstanding. Squid Boy

"Squid Pro Quo"

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MP1886 posted this 2 weeks ago

I know what the replies will be, but what would prevent one if he's on an informal range, or a range without strict rules or range officers, perhaps his own personal range, that thus person is NOT using a universal receiver rifle, from loading the rifle and gently lowereing it into the shooting position?  Or perhaps they could use the Gibson Dacron Method??

 

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John Alexander posted this 2 weeks ago

Well, what do you know, I have been using an official SAAMI loading procedure without knowing they even had one -- except for this part:

"It should be rotated slowly, end over end, in a vertical plane through 360° pausing momentarily when the powder is at the bullet end and again when the powder is at the primer end." 

This seems illogical to me. Why let the powder go to the bullet end when it has giggled all to way to the range with the bullets pointing up? This smells like something made up to impress a novice you are BSing to show how much you know, and how difficult cast bullet shooting is. We already have enough of that horse hockey in CB shooting.

Just my moderate and humble opinion.

John

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MP1886 posted this 2 weeks ago

John there are cast bullet designs that you DON'T jam into the rifling or forcing. No ways near that and they are among the best for accuracy.  I use a lot of them and they have never let me down. 

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Larry Gibson posted this 2 weeks ago

John

 

Like I said, I've no empirical data to demonstrate that cast bullets that are lightly jammed into the leade are more accurate.  Just seems they did in all my years shooting cast bullets.  Personally, I think "jam" and 'crush" are probably misnomers in they possibly give the wrong impression.  I like the bullets to be lightly engraved by the leade which seems to help center them up co-axel with the bore/throat/chamber axis, especially in looser commercial and milsurp chambers.  

The technique I use, regardless of what I or others wish to call it, are demonstratively [look at the target posted] effective.  The on-target effectiveness of what we do is what counts.

LMG

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MP1886 posted this 2 weeks ago

Here's how I see it John. You first learn how to cast and shoot cast and go out to shoot for your first time.  You gain some experience.  At this time you are in kintergarden. One of the first things you learn is to engrave the bullet into the rifling. Your shooting accuracy improves a lot at that point. As time goes on you realize that is only good for lower velocity.  If you change nothing and just try to up the velocity the accuracy isn't so good.  Engraving the bullet is just a small part of centering the bullet.  You have ensure the back end of the bullet enters the bore straight. This is where things become more difficult. Then you begin to learn engraving the bullet isn't going to get you where you need to be. 

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John Alexander posted this 2 weeks ago

MP1886 said: "John there are cast bullet designs that you DON'T jam into the rifling or forcing. No ways near that and they are among the best for accuracy.  I use a lot of them and they have never let me down."

Mp1886,

I never said otherwise so not sure why the comment. Tell us more.  if "among the best for accuracy" why don't they ever show up at matches.

John

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John Alexander posted this 2 weeks ago

Larry,

Your experience pretty well matches mine.

I agree with you that "jam" and "crush" can be misleading. To me, they imply great force and maybe distortion. Other terms or phrases can be more specific.

John

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MP1886 posted this 2 weeks ago

John 

I said it because the fit you two are talking about is the Devil and can lead you down the wrong frustrating road.  This doesn't hold true to breach seating. Then is unless you push the bullet into the bore not centered. 

Shooting super hard cast and or Linotype  or using slow slow powders isn't the Holy Grail either.  You shoot high velocity Linotype and you may very well shoot your throat out  as if with jacketed. 

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Squid Boy posted this 2 weeks ago

SAAMI experts are writing guidelines for professional ballisticians operating in labs where the use of a universal receiver is the accepted form of test equipment and the bench where the test ammo is loaded is only a short walk from the gun. If you reread the section carefully you will see that the word "twist" isn't used nor inferred. "Rotated" is the operative word used to describe turning the cartridge end for end and then tipping it into the chamber of the universal receiver. At no point do they mention twisting the cartridge between the fingers or tapping it anywhere. They are not setting guidelines for amateur's and hobbyists shooting rifles at their local club. In those cases you are free to do what works for you. Squid Boy

"Squid Pro Quo"

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Larry Gibson posted this 2 weeks ago

John

The short nose [non-bore rider] ogive of the 30 XCB bullet was tapered to mate with the leade taper of the 30 XCB reamer.  That perfect ogive to leade fit has worked very well with not only own HV (2400 - 3000+ fps) shooting but also with several others.  However, I've also had excellent results with the 30 XCB in commercial .308 and 30-6 chambers along with military chambers.  The taper of the XCB bullet did not match the leade taper in those.  Perhaps the gentile engraving which the mated the bullet to the leade has some merit after all?

LMG

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freebullet posted this 2 weeks ago

To clarify my earlier post I had error by confusing rockwell number with brinell.

Turns out I'm not perfect either, ha!

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Eutectic posted this 2 days ago

MP 1886

You were using a military surplus powder, virtually all military powder specifications include flash reduction. Since the addition of flash reduction salts costs $$ and reduces powder energy most reloading powders don't include them. No surprise the powder was working as it was designed to.

If you want to read about balancing receiver stresses, get Harold Vaughn's book "Rifle Accuracy Facts" He did it using accelerometers. Yes, it is important the receiver holes are symmetrical.  

Steve

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