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John Alexander posted this 15 June 2014

    Joe,

Thanks for putting forward some testing results -- just what I have been whining for. It is good to see some test results instead of just opinions firmly held but without supporting evidence. You have a ton of carefully gathered data that is bound to teach us something if we can sort it out. But geeeze Joe, trying to read all that in one post is like trying to drink from a fire hose. I have read it all but there's too much stuff all bunched in one place to respond to.

I have picked out one piece about which I think I maybe have something useful to say.

Joe wrote: “This is where I get stuck. A bullet with a forty-five degree filed surface for about half of the height of the base band should fly to a different place than an unfiled bullet. And with no specific orientation of the bullet with the bore, these filed-base bullets should make a “big” group. There are any number of folks who can explain why these bullets should make these big groups. They do make bigger groups, on average, I think. But, why are some filed-base groups smaller than good base groups? Why doesn't every filed-base bullet fly out of the group? Why is this a probabilistic process? If damaged bullet bases cause the bullet to fly out of the group, why doesn't every damaged base bullet fly out of the group? A cartridge without a primer doesn't go off, and it doesn't go off every single time. There's no business about it doesn't go off 96% of the time, it doesn't go off.” =================================== The type of defect you used DOES deflect the bullet a certain angle every time, just like a case without a primer not firing. Mann demonstrated it repeatedly 100 years ago and Howard Vaughn gave us the formula to calculate the amount of deflection. (Given in the Landy's report that he provided the link to in post #56 in the thread “Unexpected Fliers”.) And Landy's test of bullets with a big hole drilled in one side demonstrated it again. The reason you can't see them all forming a ring with nothing in the center is because the deflection caused by your “defect” is very small compared to size of the groups you were shooting with good bullets. For several of the series of groups you shot with and without the defect the defective groups averaged smaller than the averages with the good bullets. That was a clue that the deflection caused by the defect had to be pretty small compared to the size of the groups you were shooting with good bullets because it is not reasonable to believe that the defects improved the accuracy. If it hadn't been for the limitations of your rifle, load, skill, wind, sun, mirage and horseflies and you had been shooting .2MOA groups you probably could have shot that donut. If not you could have made the defect bigger until the deflection it caused would have produced a donut with nothing in the center. Mann demonstrated that it could be done. If you look carefully at Landy's report you can see how he could do it in his tunnel.

To use another bit of jargon, there was simply too much noise in your shooting set up and it obscured the deflections caused by the defect. I think that the most important information coming out of your tests is that defects, even pretty big ones, don't enlarge groups very much. In your tests a defect that would horrify most shooters (who “know” that even much smaller such defects in the bullet base are “very important”) didn't make a significant difference in your groups. Think about it. John

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Ken Campbell Iowa posted this 15 June 2014

out of a rifle ( system ) that can't put all shots in the same hole ... some flyers will fly toward the center of the group. in a 5 shot group it would be possible that * all * flyers fly toward the center of the group.

when i shot competition i depended on friendly fliers ... ( g ) .

BTW that's why i like offhand competition ... my 2.5 moa deer loads seem to work a lot better .

ken

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Duke M posted this 17 June 2014

Thanks Joe for all that effort and for sharing it with us.

Duke

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jhalcott posted this 17 June 2014

It did NOT happen with cast, but I once ran out of a favorite load the day before a scheduled ground hog hunt. A HASTY load program and range trip produced a 1 inch group with the rifle. The next day in the field was a disaster!!! A later range trip gave me 3” plus 100 yard groups, same gun same shooter. Only differences were letting the gun cool between shots AND groups. Also I did not run down to replace targets between groups! Friendly fliers??

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bandmiller2 posted this 17 June 2014

Joe, that was a monumental undertaking that sort of flies in the face of what we have been led to believe. The only thing I can think of is upon firing the bullet is swaged to the throat and barrel negating the minor damaged inflicted. It would have been interesting to retrieve some of the bullets undamaged by impact. Frank C.

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Ken Campbell Iowa posted this 18 June 2014

well it looks as if we can relax a little regarding small dings and wrinkles in our castings .. at least in our 2.5 moa deer loads ... thanks joe y john y bob y all others who are inputting.

but now ... how about those 2.5 - 3.5 deer rifle groups ... in a rifle that will shoot jacketed deer bullets into 1.5 moa ? i early ( but not at first !! ) found that a fat-based, nose riding cast bullet would get me down from 6 -8 moa to a plinking fool aggregation of 2-3 moa; however, in this case, LESS is better , so i am wondering ::

even if smaller voids ( offset center of gravity ) apparently is out-valued by the very high spin - stabilizing force - of the bullet .

i still wonder if a nose rider nose might be slumping enough to be ..significantly ... a cause of error.

in a 0.308 groove, 0.300 bore barrel, a nose could slump 0.004 ... if half the bullet is nose, a 180 gr bullet could have 90 gr. of nose 0.004 off center. a ” void ” 0.5 inch long, offset 0.004.

so, whatever happened to LBT 's recommended setup of full diameter full ( 80% )length contact? most shooters are using nose riders ... lyman 299 keeps do'in it i notice.

just a last thought before we slip away from the void ... ( avoid the void ) .

on a private note, my project of a super rook keeps seeming better to me .. avoids voids, gives nearly full support, and lets me cut the throat the same diameter as the grooves. win win ... what could go wrong ?

finally ( g ) .. even if my super rook works ” unbelievably ” well, does this mean we surrender and have to build a custom chamber to shoot a lot of 1 moa groups ?

more to follow, i am confident ..

ken

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John Alexander posted this 18 June 2014

Ken wrote:well it looks as if we can relax a little regarding small dings and wrinkles in our castings .. at least in our 2.5 moa deer loads .

"at least in our 2.5moa deer loads” This is true but we are losing the value of what has been learned with testing if we get it in our heads that this only applies to deer/plinking rifle/loads. It applies to much more accurate rifle/loads as well. Joe's dropped bullets show that such defects are insignificant at much better accuracy. My testing showed that the effects of some pretty big defects didn't seem to affect groups down in the 1moa range. Husker showed that truely gross defects deflect bullets only a tiny amount by cast bullet standards.

Bullet defects are just a lot less important than most shooters think and we waste a lot of bullets and time worrying about them instead of more important things.

John

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LWesthoff posted this 18 June 2014

Next question: What ARE the “more important things"? Maybe listed in order of importance............

Wes

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John Alexander posted this 18 June 2014

LWesthoff wrote: Next question: What ARE the “more important things"? Maybe listed in order of importance............

Wes Wes, I won't claim to know all the possibilities much less their order of importance but I could suggest some possibilities. My guess is that for competition, the most room for improvement is at the shooting bench not at the reloading bench. Coping with wind, mirage and consistency of hold. Spending the time shooting that we spend being very precise and tripling the time at the loading bench might get us further along. However, I think there are also things to be improved with the loads and rifles we use. I think there is a lot we don't know about maintaining a constant bore condition. Some clean every relay and then sometimes shoot several fouling shots to get to the right condition. Others shoot all day without touching the bore and do well. Tom Gray and others make a case for lube purging causing wild shots. We need to understand this better. We don't even know for sure the role “lubes” play. It is pretty clear (see Ken Mollohan's work) that it isn't lubricating in the normal sense because lead will already slide over steel fairly easily and not leave lead behind as with precision air rifles. Some bullet designs are better than others so there may be possibilities in better designs. I have heard that the two groove Springfield barrels done to increase production during wartime sometimes shoot bore riding nose bullets very well. If true, maybe we should explore wider lands to support the nose better. Or maybe the opposite would be better with very narrow lands to cause less metal displacement. How about a modified microgroove type barrel to get a better grip on the bullet? (My Sako with such rifling shows promise. What is the role of a little “choke” in the barrel? Jacket bullets don't need it and can even cope with a little reverse choke (which we sometimes get in a tapered barrel) because they are elastic. But lead bullets have very little elasticity. Would a bit of choke lapped into the bore help”? Some shooters use gain rifling. Is it better? The best aggregates at the 2013 nationals were shot using PVC wads. Should we look into that more? Is there potential in exploring subsonic loads to take advantage of the low wind drift and low recoil and torque when firing? I'm sure others could add to the list. John

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LWesthoff posted this 18 June 2014

Okay! I agree wholeheartedly with your first choice. I believe that for most of us, bench technique is the number 1 cause of low scores and loose groups, and also probably for wild shots (too often referred to as “flyers"). That would be especially true for shooters who, like me, shoot Production Rifle and Military Issue. For those of us who shoot these categories, bench technique improvement is about the only way we can go.

I haven't the faintest idea what comes next, but I'm pretty sure of one thing: the answer is going to come from the Unlimited class. They're the ones who will answer the questions about barrel choke, rifling style, and such.

I have no desire to join those guys, but I'm going to be very interested to see what kind of ideas they come up with.

Wes

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John Alexander posted this 19 June 2014

LWesthoff wrote: Okay! I agree wholeheartedly with your first choice. I believe that for most of us, bench technique is the number 1 cause of low scores and loose groups, and also probably for wild shots (too often referred to as “flyers"). That would be especially true for shooters who, like me, shoot Production Rifle and Military Issue. For those of us who shoot these categories, bench technique improvement is about the only way we can go.

I haven't the faintest idea what comes next, but I'm pretty sure of one thing: the answer is going to come from the Unlimited class. They're the ones who will answer the questions about barrel choke, rifling style, and such.

I have no desire to join those guys, but I'm going to be very interested to see what kind of ideas they come up with.

Wes Well Wes, finally we seem to be in almost complete agreement on this set of things.

I too only shoot production rifles and don't modify throats or bump bullets. Those are just the limitations I put on myself because I enjoy seeing how well I can get a production rifle to shoot.

I agree that bench technique is probably the most productive thing for production/military shooters to work on. I'm not sure we have found the very best way to feed the this type of rifle but we may be close.

I also agree that the unlimited guns have the best chance to answer the question about what it takes to break through the .5 MOA barrier (for an average of match fired aggregates on a regular basis.)

I wish those shooting heavy relatively easy to shoot guns; UNR, UNP, Heavy, and PBB (all shoot nearly the same sized aggs) would do more experimenting with things other than what you might call tweaking of loads.

John

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joeb33050 posted this 19 June 2014

LWesthoff wrote: Next question: What ARE the “more important things"? Maybe listed in order of importance............

WesSure. Easy.1. Rifle-buy a new Sav/Rem/Win/TC/ any = ANY new bolt action rifle in 308 or 30-06.2. Scope-buy at least a 3-9X PARALLAX ADJUSTABLE scope and good mounts. Today's $130 scope is 90% as good as today's $2000 scope.3. Bench rest/bags. Buy a decent bench rest and bags. The Hoppe's rest and decent bags = 90% as good as the $750 wizardy machinist's orgasm bench rest with 17 knobs.4. Information-buy some books. Lymans CB handbooks, “The Accurate Rifle” by Warren Page tells you how to shoot from the bench. 5. Equipment-buy good brass, mold, lube, gas checks, primers, powder, ...6. Follow a sensible recipe. No Abysinnian Knurlman mountain rifle, no Clevinger made-in-the-cellar #56-2 powder, no primers made from kitchen matches, nothing strange and/or stupid. Do this, practice, write it down, experiment sensibly and you'll be shooting around 1.5” 5 shot 5 group 100 yard averages.

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John Alexander posted this 20 June 2014

Ken wrote: i still wonder if a nose rider nose might be slumping enough to be ..significantly ... a cause of error.

in a 0.308 groove, 0.300 bore barrel, a nose could slump 0.004 ... if half the bullet is nose, a 180 gr bullet could have 90 gr. of nose 0.004 off center. a ” void ” 0.5 inch long, offset 0.004.

Ken, Of course the closer to the nose the less likely to get upsetting of the bullet but it may still be happening fairly close to the nose with some loads. If we had more CB shooters catching bullet without damaging them we would know things like this. I am working on a catcher but Joe says I will be the laughing stock because of the embarrassing failures. Been there done that so will go ahead and try.

so, whatever happened to LBT 's recommended setup of full diameter full ( 80% )length contact? most shooters are using nose riders ... lyman 299 keeps do'in it i notice.

Us unwashed types in hunting rifle or in the military rifle classes are shooting nose riders. But many, if not most, of the big dogs with the rifles that may give you a hernia getting them to the bench are shooting those .5MOA groups with a bullet bumped to a taper in a die made with the same reamer as made the throat. Extra cost and extra loading steps but hard to beat.

John

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Ken Campbell Iowa posted this 20 June 2014

john a. sez: But many, if not most, of the big dogs with the rifles that may give you a hernia getting them to the bench are shooting those .5MOA groups with a bullet bumped to a taper in a die made with the same reamer as made the throat. Extra cost and extra loading steps but hard to beat.

ken sez: so as to not lead lead ( g ) cast bullet shooters to think we need 50 lb rifles to shoot .. 0.5 moa and under, i observe that by far the majority of centerfire mj benchresters are using varmint wt. rifles to shoot their 0.2 moa groups.

i think mj bullets do a good job of self aligning .. especially in a chamber that it takes me at least some 8 hours to cut to 0.0002 inch concentricity.

for example, my factory 40X 22 lr bench rifle came with a crooked throat ..when i ( set back rechamber ) fixed it the groups ( lead bullets ) were cut in half.

i think lead bullets do NOT self align ... maybe almost not at all ... so again, maybe we need special chambers to shoot 1/2 moa and better. not all bad ... such ” special ” chambers wouldn't be so ” special ” if remington ... savage ... would take an extra 5 minutes and cut them that way; not likely because of 100 year old saami specs so that all ammo works in all guns. ... all saami bullets are unsupported in all saami guns ( g ) .

oh, speaking of bullet support; when we think of tapered bullet fitted to a tapered chamber .. it is easy to get a mental image of a morse taper fit in a morse taper sleeve ... locked tight and perfectly straight. so, gee i did a little math and found that for full support over a one inch long bullet ... in a normal 30-06 barrel ... it takes a ONE-SIDE taper of 1/4 degree ... or 1/2 degree included angle. ( for those who want to play, google up a table of ARCTAN values. ). hmmm microgroove shallow rifling would be even less taper ..

more to follow

ken

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DAMAGED BULLETS

I have picked out one piece about which I think I maybe have something useful to say.

Ken wrote:well it looks as if we can relax a little regarding small dings and wrinkles in our castings .. at least in our 2.5 moa deer loads .

in a 0.308 groove, 0.300 bore barrel, a nose could slump 0.004 ... if half the bullet is nose, a 180 gr bullet could have 90 gr. of nose 0.004 off center. a ” void ” 0.5 inch long, offset 0.004.

so, whatever happened to LBT 's recommended setup of full diameter full ( 80% )length contact? most shooters are using nose riders ... lyman 299 keeps do'in it i notice.

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