I got TFS No. 234 Monday, and read it all, including Tom Acheson's article on case neck tension. Wednesday I went to the Trail Glades Range in Miami. There was a new serious benchrest shooter there; there have been less than half a dozen serious benchrest shooters there, when I was there, in the past 14 years. A serious benchrest shooter is easily identified; he has a rifle that others stop to look at, a powder measure, and an arbor press. This guy was shooting a .20/223, sort of a .204 Ruger. An hour into shooting he came over, looked at my rifle and lead bullets, and began to talk about neck tension and accuracy. He didn't say “neck tension”, but he described the varying force required to neck size, to expand necks and to seat bullets. He explained about the need for exactly equal case lengths, for turning necks, for measuring turned necks and segregating cases by neck thickness variation-or discarding nonconforming cases. He explained about his equipment for trimming, turning and measuring case necks, the perils of the “doughnut”, what work hardening is, annealing and his annealing machine. He told about the better benchrest shooters and the 1000 yard guys, how they were absolutely and universally convinced that necks were crucial, and that they annealed after every firing. He said that he sometimes went as many as three to five firings between annealings, but intimated that annealing every time was best. This accompanied by recurring explanations of work hardening, in case I'd forgotten. Now this guy was sincere, he had the gun/s and equipment indicating that he was serious and knowledgeable, and he's a fiery-eyed zealot/proselytizer about neck tension. The man probably said a lot more, but being deaf as a haddock I missed it. This was not a discussion, questions were not allowed, it was a sermon. My position on neck tension is that I throw out any case with unusual force required to size, expand necks or seat bullets. I keep cases together by lot, starting with ~120, shoot them in order so each is fired ~ the same number of times, and anneal all when the first neck splits. My cases last a long time, many firings. I don't have an opinion on neck tension vs. accuracy; the TFS has articles with conflicting conclusions. But I now know someone else with a firm opinion.
Neck tension
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- Last Post 12 February 2016
I like uniform neck tension were every bullet seating feels the same.
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I seem to load more concentric ammo using less neck tension and turned necks. But I have no proof these cast rounds shoot more accurately. There is never enough range time for me.
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I don't have a horse in this race, but it seems to me that John Alexander's suggestion (last paragraph, in italics, on p. 234-24) is worth implementing.
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If there was no neck tension would the bullet fall onto the top of the powder column? Otherwis if it doesn't then neck tension exists, yes/no? Probably becomes a case of sliding fit to interference fit or somewhere beyond that.....
Tom
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If there was no neck tension would the bullet fall onto the top of the powder column? Otherwis if it doesn't then neck tension exists, yes/no? Probably becomes a case of sliding fit to interference fit or somewhere beyond that.....
TomI think that there's no neck tension with breech-seated bullets, and we've seen the good accuracy with these. As explained here in the past, I shoot semi-breech-seated bullets in 30-30, 45-70 now, have done for years-these and other guns. Push the bullet in, put the case in, neck around but not holding the bullet. Forgot the 32-35, same semi there.Works for me. Does no-neck-tension make these guns accurate? I don't know.I use the method because I don't have bullets that will breech seat all the way.
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I keep looking at Tom's article in TFS 234 on neck tension. If I understood and copied the numbers from the article correctly, there were (16) 10/200 groups shot in Season 1 and (14) 10/200 groups shot in Season 2. All otheer averages are of (4) groups.The SHOTS/RANGE YARDS, group averages and percent average group size reductions are copied below. 10/100, 1.689” TO 1.496”, -11% 5/100, 1.325” TO .6785”, - 49% 10/200, 4.226” TO 2.011” ”€œ 52% 5/200, 3.209” TO 1.605”, -50% I don't know if neck tension affects accuracy, but I have a very strong opinion that reducing the neck sizing bushing ID by .001”-.002” which sizes the neck smaller and increases neck tension will not reduce group size anything like 50% as this data suggests. Either there's a statistical williwah happening or something else changed, or both. If my opinion is incorrect, then anyone with the appropriate neck sizing dies/bushings could demonstrate this large change in a few hours shooting and open up a new path to accuracy.
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Joe,
There is one component missing.....me. Even though these groups were shot under match conditions, not cherry picked weather, every time you sit down behind the bench you the shooter are a different person. This isn't a science and we aren't machines so our results will vary. But how do you graph that? What factor do you apply to “normalize” the results? Maybe it's a lot like fishing. You go to the lake and see what happens. There are some things we just can't control. We can influence them but not fully control them. And this is an XP-100 not a Unristricted pistol. The max weight is 7-pounds, not any weight you want. And you have to have consistent grip pressure from shot to shot. This thing jumps and twists during recoil. The consistent grip pressure is one thing I really struggle with. Somedays it works and somedays it don't work as well. And that's why they call it fun....you just never know....
Tom
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Finding some answers by a few hours of testing is something that could be done not only for neck tension but also for a lot of other cast bullet casting and loading procedures that are based on opinion, conventional wisdom, and flawed logic -- but not on facts found by testing. As far as neck tension is concerned, an excellent test has already been done even though the results seemed to have been ignored. Gerry Bottiger reported in the 2013 July/Aug. Fouling Shot (#22) on a well designed series of tests he did to see how much influence neck tension had on velocity and accuracy. He found absolutely no difference in either based on neck tension.
There has been some doubting and theories suggested since Gerry's article was published to try to claim neck tension does make a difference but no test results to challenge Gerry's results have been offered.
Gerry's tests were conducted with a rifle and load shooting approximately 0.5 MOA for five shot groups. If no effect could be shown for different neck tensions at this level of precision it is not likely that it affects the results of folks like me averaging 1 MOA on a good day.
John
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If there was no neck tension would the bullet fall onto the top of the powder column? Otherwis if it doesn't then neck tension exists, yes/no? Probably becomes a case of sliding fit to interference fit or somewhere beyond that.....
Tom
Sort of, generally.
To reduce the influence of variations in neck tension WHILE reducing the variation of location of the bullet (axial alignment and such) I size only minimally (to keep the body of the case as close fitting to the chamber as functionally possible and then expand for a specific DEPTH and DIAMETER that allows the bullet to JUST slip into the case and stop at a consistent place. It is close enough in diameters that when the bullet is lubed there will be enough resistance to movement provided by the lube to keep the bullet in place during handling.
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This may not be germain but the dimension of the neck in the chamber is 0.332” and a loaded round (Lapua cases, neck turned) was 0.331” OD. So there is very little clearance once a round is chambered. If I recall correctly, the bullets were seated about 0.025” too long and closing the bolt pushed the bullet back into the case, at the same time being engraved by the rifling and (hopefully) centered in the chamber. I suspect that changes in bullet hardness would influence the amountof of bullet travel when closing the bolt. The alloy in many situations was 50/50 lino/mono and the bullets were “bumped".
But.....that short article at least got a few of you offering opposing views which is what I was hoping for. I need all of the research I can get to try to get this new chambering (30/223) to shoot like the 30 PPC.
Thanks guys!
Tom
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I hope this might be of some interest in this neck tension discussion. I believe this story originated with Phil Sharpe, but I can't say for sure. Many years ago, the Gov't was having trouble with copper fouling in the service rifle. (Springfield, I believe.) So, after experimenting, they discovered that alloying the copper with tin greatly reduced the fouling. Some years later, they began to have trouble with rifles being damaged/destroyed by what seemed to be excessive over-pressure. They investigated the ammunition by pulling the bullets, and checking powder quantity, instability, etc. You can imagine the drill. Finally, someone suggested checking the bullet pull, which, as I recall, was specified as 35 lbs., plus a nominal tolerance. To their amazement, the tensiometer showed some rounds with a pull of over 200 lbs. It developed that the tin used in the alloy had caused the bullets in some cases, to be actually soldered to the case mouths. So, they changed to an alloy containing Nickle, which solved that little problem. While slightly off-subject, I hope someone finds it interesting. Bill
In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.
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Thanks Bill I found it interesting and I'm sure others will. Soldered in bullets are probably not a good thing. As long as the subject of neck tension has come up I should say that I have corrected post #9. The fouling shot that refers to Gerry Bottiger's article on the subject. It is in TFS #224, July-Aug. 2013 - not where I originally said it was.
Anybody who thinks variations in neck tension affects rifle accuracy should read this article -- and then read it again. Gerry reports on a well designed test where two sets of loads were as identical as he could make them with the exception of neck tension and groups of each were shot alternatively in the same conditions while comparing velocities and group sizes.
The neck tensions in one set of loads were almost twice the neck tension in the other. Yet Gerry found no significant difference in either velocity or accuracy and since accuracy for Gerry and this rifle means averaging .5 moa we should think about that.
Theory often leads us astray so we should be skeptical but maybe a little theory might be helpful for those that find it hard to believe that neck tension doesn't have any effect on velocity or accuracy in a rifle. The two seating forces in Gerry's ammunition were approximately 30 and 60 pounds which are typical. It may be helpful to consider that while the bullet is being urged out of the case neck by expanding gas, the force (pressure x area) on the bullet base is in the neighborhood of maybe 2,000 pounds or more. Considering how tiny neck tension is compared to the pushing being done it doesn't seem so amazing that changing from 30 to 60 pounds of seating pressure has no measurable effect on anything important. Difference in neck tension are simply in the round off error of the 2,000 pounds which is varying from shot to shot far more than the 30 pound difference in neck tension.
Of course rough estimate above of the forces involved assumes there is any neck tension when things go bang. Maybe the first thing that happens is that the pressure expands the neck before the bullet moves much leaving the rear of the bullet hanging in air with no neck tension at all.
John
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I think everyone here can safely assume I don't know what happens at the moment of ignition, but as far as neck tension goes I believe the last sentence of John A's post seems most likely. GP
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I was going to start a thread asking how many guys on here turn necks on their brass......but I think I get the idea from reading this thread.
I had never contemplated neck turning, thinking it to be only for the guys wanting to shrink groups by a few thous to beat the next benchrest guy, but there is one aspect of it that I wonder might help the “average” handloader.
I sometimes have a horrible time with seating my bullets straight. I can do all the prep on the cases the same way - cleaning, sizing, flaring the mouth, etc - and take care of how I seat, but still wind up with some that are just a little out of concentric with the case.
I do not have a factory made tester to see this which makes it worse because I can see it with just my eyes(I do have a homemade spinner). I can also see the results when I sort the bad ones from good ones and shoot them.
I have gotten better results since I started using the Hornady seating die with the floating sleeve, and I have some expanders coming from NOE that are supposed to work like the Lyman M type. I have to wonder if this is where I will see my largest improvement in concentric rounds. Can anyone say that they saw a dramatic increase in consistency when they started using a good expander over the standard expander in a die and then just flaring the case neck?
So for me, the thought of neck turning wasn't so much about bullet pull/tension as it was how it might effect bullet seating and the bullet being straight inline with the bore each and every shot.
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I don't have extensive test results to prove it, but it is my belief that proper neck tension and the resulting concentricity of loaded bullets are directly related. If there is excessively tight neck tension, it stands to reason that it can cause issues when seating a cast bullet which is much more malleable than a jacketed bullet. I try to have .0015"-.002” neck tension. I can say that holding to this standard along with some other steps that I take in my loading process have shrunk my group sizes greatly. Since I made multiple changes at one time, it's hard for me to say how much difference neck tension made but I am convinced it is a positive step.
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highstandard40:
I agree with what you wrote especially the part about neck tension and concentricity being directly related. And my results have been the same.
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I got both of the expanding stems that NOE offers. If I am reading their sizes correctly I may have to do some modifications to one in order to make it fit right.
The expanders are labeled .226x.222 and .228x.224. I am going to guess that .228x.224 is what I will be using. I size my bullets to right around .2255". I figured I would use the other for jacketed bullets.
My plan is to take the stock expander out of the sizing die and just run the case up in it sizing the neck. Then run them through the expander to open up the necks and give that little step for the bullet to sit in while going into the sizer. My hope is that all of it combined will amount to more concentric rounds.
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Newt:I used to turn necks for my 600 yd. slow fire stage of the NM Course; couldn't tell any difference in score, pro or con, but it was a pretty superficial test. Kinda forgot about it. A few years ago, I bought a Hornady Concentricity Gauge; a very well made tool. I found that the worst (the very worst condition) showed a few bullets to be .0015” out of concentricity; most were less than .001. So, I tried the Gauge on my cast loads; same result; a max. of .0015". I straightened the rounds, then began wondering if I was truly straightening the round, or if, perhaps, I was, in fact, actually bending the bullet. I still don't know, but I quit checking for concentricity as it didn't help accuracy; neither did it seem the neck turning helped. Bear in mind that this “test” was as unscientific as it may come, and we're not talking world-class groups, either, but purely Observational convention. Bill
In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.
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Hmmm. 1-1/2 thousandths TIR is GOOD. You've got a grip on it Bill!
(Factory ammo runs .015 down to maybe .004 give or take; army FM lists .004 or better for 'match' ammo.)
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I would think .002” runout would be ok. I'm just looking to get it down as far as possible with normal tools. I am not measuring them so I don't know the exact amount. I just know that it is enough that when I separate and shoot groups the difference is very noticeable, like inches.
For those of you who do measure run out, what have you noticed made differences? I did check how the shell holder lined up on the seating die and there was a noticeable gap. So I moved it to another press that lined up near perfect far as I can tell.
Have not tried seating yet, still waiting on the expanders.
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my benchrest mj buddies tell me they don't panic until runout is edging upward of 0.0015 .... of course that doesn't keep them from trying for zero ...
i am not sure, but always hoped that lightly engraving the bullet nose would straighten up the bullet .....but if there is case-neck runout that would help a lot less .
ken
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I don't pay much attention to neck tension since I started using FL Size neck bushing dies. But do watch loaded round concentricity. “Concentricity is king"
But then I'm just a military match shooter so what do I know?
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A bullet that is concentric (near perfect circle) and fits throat snug and centered is more important. Chamber and throat must me cut inline with bore also.
I like just enough neck tension (looser) that will allow bullet to be pushed all the way into throat and centered when chambered...no matter how non concentric the loaded rounds are.
I set the case shoulder back .001-.002 by full length resize...this helps center the bullet better without bullet binding in throat before firing.
I think I am getting better at this cast bullet thingy. (excuse the weak writing)
...
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Here's what I learned about neck tension. The main thing isn't if you have neck tension or not if you are single loading. But it needs to be consistent. I had some match cases where seating the bullet didn't feel the same. The oddball didn't shoot into the group.
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So is there anyway to get consistent tension other than neck turning? Do the Lyman M type expanders do it even with different neck thicknesses?
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Newt, I would think that the ultimate way to get consistent neck tension would be turning the necks, annealing often, and using a proper M die. I have never turned case necks myself but I do have all custom neck expander buttons and I am in the process of building an automated case neck annealer.
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Here we are worrying about neck tension again -- one of the most persistent Zombies.
If variation in neck thickness affects runout maybe there is a case for worrying about it although I think bullet fit in throat (and in bore for bore riders) is waaay more import than runout because good fit will fix most if not all runout when chambered.
However, I think the facts show that worrying about variation in neck tension itself is a waste of time. As far as I am concerned Gerry Bottiger (see my post #9 and read the FS article) killed it dead even at the .5 MOA level with his experiments. It is even less likely to amount to a hill of beans at accuracy levels several times as big.
For those like to know why it isn't important see my post #13.
John
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Yea, I am not so much concerned with neck tension for what it is as much as I am curious of its effect on concentric rounds. I see what your saying about runout being fixed, in sorts, by good fit, but in my situation thats not the case.
So I could have my throat reamed out to fit my bullet, or get a bullet to fit my throat, or I can figure out how to eliminate as much runout as possible. After reading all the posts and documentation I can see that neck turning for tension sake is pointless to me. But it did make me wonder if it was an easy way to help the runout issue.
I guess one guys tomatoes is another guys potato. :)
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There was a post by Tom Acheson about a year ago or so on the forum that suggested that adjusting neck tension did have an effect on accuracy. Tom's results were documented over a season of shooting and were validated with the stats.
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There was a post by Tom Acheson about a year ago or so on the forum that suggested that adjusting neck tension did have an effect on accuracy. Tom's results were documented over a season of shooting and were validated with the stats.
RD,
Yes, I remember Tom's post well. However, Tom's results involved two seasons instead of one. He changed the neck tension he was using between seasons and as I remember did better (although it could have been worse.) Whether better or worse, and with all due respect to Tom, it goes without saying that several other variables changed between the seasons along with the neck tension. Tom may have gotten better or worse or practiced more or less. Surely the weather conditions changed. The list of possibilities is pretty long.
I have great respect for Tom but in my opinion comparing one year to the next isn't a good way to test most things because things change in a year.
I believe if you really want to know weather load A or B is best you had better shoot the groups alternately on the same day and try to keep everything else the same. Even then it is hard enough to get a reliable answer, as we see with Ric's excellent test.
John
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Yea, I am not so much concerned with neck tension for what it is as much as I am curious of its effect on concentric rounds. I see what your saying about runout being fixed, in sorts, by good fit, but in my situation thats not the case.
Newt,
You are absolutely right. With many heavy class rifles the bullet is swaged (bumped) in a die cut with the same reamer that cut the throat so the fit is near perfect. A well fitted long bore rider also has a lot of contact over a major part of the bullet. Others not so much especially in production chambers.
John
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So is there anyway to get consistent tension other than neck turning? Do the Lyman M type expanders do it even with different neck thicknesses?
Basically yes.
I don't know what rifle/chamber you are working with so ..... anyway,
Zero or 0.001"neck tension offers the most bullet adjustment (correction in the chamber). Some powder choices may burn better with more tension or pull.
You can choose the amount of your neck pull or fit a few ways.
Can you put your ready to load bullet into an unsized fired case? Likely, ... right? If not you have other troubles.
So, you can use a neck sizing bushing (in a bushing die) With this system- However thick your cases are, you can choose a diameter to get what you want on the inside.
Or, use an M-die neck expander or something like it. M-dies are cast bullet friendly but are one size (mostly) for a caliber. M-dies are OK but if you can choose any size you want, that is better.
If you don't have a lathe or a friend with one to make any size needed you can contact Buffalo Arms Co (BAC) and get any size you want from them -BAC expanders use your stock die body from a 2 or 3-die set.
Maybe this helps?
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John: My reply noting Tom Acheson's post regarding his findings with regard to neck tension previously was for anyone who had not seen it and might like to read another side of the discussion from an experienced shooter. It can be found in the archives by using the search. And, yes, Tom's data covered two years of shooting. I posted from memory so thanks for pointing that out. So are you saying that the data and results that Tom posted reference neck tension are not credible or valid? And what are the several other variables that changed during the season that could have effected his final data positively? Were you shooting with him? Tom states that the conditions over the course of two years were not "cherry picked” but his results still suggested that the average group measurements got smaller with a change in neck tension over two years. And he provides the facts to support his results. Any way, that's my interpretation.
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Rd, The tone of your post suggests that I my last post annoyed you. If i did, I didn't intend to and apologize.
I agree with your interpretation in your last paragraph. -- the groups did get smaller.
I was just suggesting that changing one controllable variable and comparing two seasons of shooting leaves a lot of uncontrollable variables and suggested a couple. Everybody can make up their own mind which observations or reports are likely to be most credible. My opinion is that the evidence from Tom's observations are not as strong as evidence based on the results of a controlled test with both options fired under the same conditions like Bottiger's. Others, of course, are entitled to other opinions.
John
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So is there anyway to get consistent tension other than neck turning? Do the Lyman M type expanders do it even with different neck thicknesses?
Basically yes.
I don't know what rifle/chamber you are working with so ..... anyway,
Zero or 0.001"neck tension offers the most bullet adjustment (correction in the chamber). Some powder choices may burn better with more tension or pull.
You can choose the amount of your neck pull or fit a few ways.
Can you put your ready to load bullet into an unsized fired case? Likely, ... right? If not you have other troubles.
So, you can use a neck sizing bushing (in a bushing die) With this system- However thick your cases are, you can choose a diameter to get what you want on the inside.
Or, use an M-die neck expander or something like it. M-dies are cast bullet friendly but are one size (mostly) for a caliber. M-dies are OK but if you can choose any size you want, that is better.
If you don't have a lathe or a friend with one to make any size needed you can contact Buffalo Arms Co (BAC) and get any size you want from them -BAC expanders use your stock die body from a 2 or 3-die set.
Maybe this helps? I am working with .223 in Rem M700 if that helps. Sized bullets slip/fall in and out of a fired case. I did get some expanders, M-type, from NOE. Tried them out last night. I got the two they offer for this application. .222” stem with a short .226” shoulder, and a .224” stem with a short .228” shoulder. I can already see that the smaller one will only be used for jacketed bullets. But the larger one is a perfect match from what I can tell. My bullets are sized to .2255” I have not got a chance to do much in the way of testing, but it seems that the neck tension is a bit less than when I was using the expander inside the FL die and just flaring the mouth to not shave the bullet. Now the steps I am taking are; using the FL die without expander/decapper and set to only size down to the case neck/shoulder junction. It does size/touch the outside of the case, but does not bump the shoulder back(this was checked with black soot). Then I run them up into the new M type expander which is set to use that short .228” part deep enough to come to the top of the gas check. Then run them into the seater. The few I did try the tension did seem lighter than normal, and more even. I did do a dummy round to see how much pull it took to get it out and it is significant. More important, to me, was that it seemed each round was concentric. I really need to get/make a better guage to test this with before I am certain though. I am going to guess that having too much neck tension before was indeed killing my ability to seat evenly. But, who knows. I'll be loading up some test rounds now because I am willing to bet I'll have to find the best powder charge again. I was using 8 grains of Unique.
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John: Feathers, annoyed ?? For asking you to clarify and support what you wrote?? Not likely. Could be wrong but I think something is missing here. You wrote: “Everybody can make up their own mind which observations or reports are likely to be most credible" If you reread my initial reply, you will realize that the above was precisely my Point. The end. Now back to the regularly scheduled program
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I have given some more thought to Bottiger running a good test and finding that variation in neck tension caused neither a change in accuracy nor anything else and Tom's observation that changing the neck tension changed how well he did the next season. I don't think those results necessarily counteracted each other.
I can think of a couple of reasons why Tom's neck tension change could indeed have been the reason he had a better or worse season. If the first sizing wasn't enough to fully seat the bullet in the throat the same every time thus having a varying fit to the throat. increasing the neck tension could have improved things.
Having the neck sized to small causing some slight sizing or other damage to the bullet could also have changed things but I believe Tom said things improved the second year. I'm sure there could be other such reasons.
I have never claimed that you can't foul things up while sizing the neck -- you can. What I was trying to say, apparently badly, was that it a waste of energy to worry that accuracy might suffer from the small changes in neck tension from one round to the next. The kind you detect as variation from one round to the next in the force needed to seat the bullet. Bottiger's test results indicated that this worry is groundless.
John
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I am working with .223 in Rem M700 if that helps. Sized bullets slip/fall in and out of a fired case. I did get some expanders, M-type, from NOE. Tried them out last night. I got the two they offer for this application. .222” stem with a short .226” shoulder, and a .224” stem with a short .228” shoulder.
OK! You are out ahead of the game with already having the custom expanders.
I read what you are doing and that is what I would do to.
I think it might be interesting to seat and pull a bullet to see if it comes out measuring the same or very close to what it went went into the case neck. Also inspect for damage or shaving
But, sounds like you know this.
Soft alloy v hard and tight neck pull v loose can create unseen problems so it is good to pull assembled rounds apart sometimes.
With Unique powder, very loose bullets should still work fine. However, maybe not so with hard to start powders. Also, if you want to seat the bullet into the rifling hard, a loose neck may give you different bullet (OAL) length from one shot to the next and as you know that might mess with both velocity and accuracy. You likely know all this but I thought I would cover it anyway.
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Never hurts to bring up valid points. I have pulled a bullet or two to measure and they do stay the same diameter. I am using a 5:2 WW:lino mix, supposed to closely imitate Lyman #2?
Good to hear I am on the right track, or at least the same one another person is on. I just tried to think logically about it all, and do what I can, with what I have or can afford.
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Newt,On the subject of neck tension, I have a couple of thoughts. If you are seating your bullets so that they are into the riflings, variations in tension may cause some bullets to be engraved slightly more than others, hence the pressure to overcome initial inertia and friction may vary. I have modeled pressure build using Quickload. I'm quite sure that the neck begins expanding before the bullet begins moving. If that sounds strange, pressure needs to reach a few thousand psi for forward motion to begin. This might suggest that the bullet is suspended in space momentarily before forward motion begins. I might consider varying seating depth with your preferred load. If you would like, I could send you some cast bullets made of Linotype. The mold is NOE 55 grain. I have very limited experience with this bullet, but in my 22-250 with 14 twist, I am encouraged with results.Loren
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Thanks for the offer Loren, but no need to send some.
They are into the rifling, but that was mainly because its where I originally found my best grouping. I cant say for absolute, but I would be willing to bet I got better groups because forcing them into the lands caused some of the bullets to straighten out some.
I do know that I first started shooting the jacketed jammed into the lands and once I backed off I started getting the tighter groups. Very noticeable difference.
So I will play around with depth for sure. Thanks for bringing it up. One other reason I thought might have been why the loads shot better jammed is because anything less than jammed and the gas check/base goes past the neck into the case. I was not sure if gas cutting was playing havoc with the bullets or not.
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If you are forcing the bullets into the lands doesn't that make neck tension kind of an moot point? I would think that it should take a great deal more pressure to overcome the friction and inertia of a land engraved bullet as opposed to overcoming any reasonable neck tension. I realize that some powders need the bullets to be tightly crimped in order to burn completely or thoroughly ( as in say the 44 mag with heavy charges of slow burning powder and light bullets for an extreme example), but if you are shooting that same combination of load in a single shot rifle would not jamming the bullet into the rifling accomplish the same thing?
Does anybody know where we can get one of those pressure measuring devices that you place the sensor on the barrel and hook up to a computer. They are supposedly quite sensitive and will give you an idea of pressure differences between land engraved bullets and how much the neck tension affects pressure of not. Brodie
B.E.Brickey
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If you are forcing the bullets into the lands doesn't that make neck tension kind of an moot point?
I would think that it should take a great deal more pressure to overcome the friction and inertia of a land engraved bullet as opposed to overcoming any reasonable neck tension.
I realize that some powders need the bullets to be tightly crimped in order to burn completely or thoroughly ( as in say the 44 mag with heavy charges of slow burning powder and light bullets for an extreme example), but if you are shooting that same combination of load in a single shot rifle would not jamming the bullet into the rifling accomplish the same thing?
Does anybody know where we can get one of those pressure measuring devices that you place the sensor on the barrel and hook up to a computer. They are supposedly quite sensitive and will give you an idea of pressure differences between land engraved bullets and how much the neck tension affects pressure of not.
Brodie
Not quite. The bullets will still shoot out of the group if there is not uniform neck tension or un-tension. It needs to be the same from shot to shot.
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If you are forcing the bullets into the lands doesn't that make neck tension kind of an moot point?
I would think that it should take a great deal more pressure to overcome the friction and inertia of a land engraved bullet as opposed to overcoming any reasonable neck tension.
I realize that some powders need the bullets to be tightly crimped in order to burn completely or thoroughly ( as in say the 44 mag with heavy charges of slow burning powder and light bullets for an extreme example), but if you are shooting that same combination of load in a single shot rifle would not jamming the bullet into the rifling accomplish the same thing?
Does anybody know where we can get one of those pressure measuring devices that you place the sensor on the barrel and hook up to a computer. They are supposedly quite sensitive and will give you an idea of pressure differences between land engraved bullets and how much the neck tension affects pressure of not. Brodie RSI makes one. You can get the entire setup for less than $800. If I had more time, I would buy one in a heartbeat. But to make use of it you would need to spend a lot of time with it. I hope that the neck tension works well. I loaded up my test rounds last night, so when I get a chance to shoot I'll be set to go. What was very interesting/different is that all the bullets seated with the same pressure. What I did not like was I could still see that some rounds were still not seating straight, they were not concentric. The neck tension is minimal and I do not think I could go any lighter. In fact, it is relatively easy to move the bullet back, and side to side. Being a bolt action I have no issue with this, and wonder if it will self center better than before. I guess testing will provide the answers.
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Bill commented on Brodie's post: "Not quite. The bullets will still shoot out of the group if there is not uniform neck tension or un-tension. It needs to be the same from shot to shot."
This alleged inaccuracy because of variations in neck tension is exactly what Gerry Bottiger couldn't find in his elaborate tests. What Gerry did find was that one level of neck tension averaged .509 MOA, rounds with DOUBLE the neck tension averaged .545 MOA, and groups with a mix of light and heavy neck tension averaged .409 MOA. This indicates that rounds with a variation of neck tensions shoot quite a bit better than ones with uniform neck tension. This is silly of course but should make a strong point. Gerry has won back to back national championships in two different CBA classes so these numbers are what he does fairly often.
Gerry also had some rounds that had much higher neck tension and they all shot into the groups.
Since the topic of concentricity has been discussed in this thread I will mention that Gerry had some rounds with runouts over .003.” (Which I suppose looks bad to a guy averaging .5 MOA.) He reported that none of these cockeyed rounds enlarged his groups.
In IMHO it seems like us ordinary mortals averaging between 1 and 3 MOA should probably pay attention to these results unless we have evidence of a similar high quality experiment that says otherwise.
John
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Thanks for that information John. That makes me feel much better about the runout I am seeing. I don't have a way to measure them, but would guess that my rounds now don't have much runout to them. But before I can guarantee it was well above .003", probably in the .010"+ range.
While I wasn't looking for neck tension for bullet release sake, I think I will find that the lighter tension I do have now will help. I know that this change alone has helped with runout, unless its just something to do with the M type die.
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John, Here's how I tested my match cases once I'd formed, neck turned them, weighed them and apparently by some, shook chicken neck bones over. Oh, did I forget, make sure the primer holes are to a uniform depth also.
I'd then load the cases up and shoot them. I noticed that the ones that the bullet felt looser when seating did NOT shoot into the same group. It's easy to see which ones are forming a group if the group is about .6". Conversely it's easy to see which ones do not shoot into that hole.
The difference was that the neck tension was not the same as the other cases. The gun had the bullets seated by hand as the chamber was an Ardito throat with matching bumped bullets.
I also confess to being (back when I had a loading/casting area in a garage) to subscribing to other details not considered by some. I made sure my cases were weighed before I fiddled with them. They were Lapua so not much was needed other than making sure they weighed with in a .2 grain range or less. I typically picked about 15 cases that weighed almost the same and shot those.
I neck turned them and tried to keep the neck thicknesses within .002” This is very hard to do as just holding the neck turning tool in your hand warms it up and causes dimensional changes.
I weighed my bullets to keep them the same. Most of the time my bullets were within the same .1 grain range. That's easy to do if one casts up about 1600 bullets and sorts them first for defects (and discarding those) and then by weight.
I cleaned primer pockets every 2 or so reloads. It didn't seem to have much of an impact if the case was fairly clean. I did have to pay attention to the shoulder lengthening. If the case chambered hard because of long shoulders it would also shoot out of the group.
The thing I didn't fiddle much with was the powder charge. I'd do a version of ladder testing to find one of the three “nodes” or “sweet spots” since those spots are more forgiving about 1/10 grain or so difference in powder weights, I'd just use a Harrells powder measure and throw those. The powder charge would need to be changed up or down based on the temperatures that day. I did find out one time in a Regional shoot that I should have backed the charge down a click or two as 104 degees caused my groups to open up. I usually did my load testings at way cooler days.
Now back to tossing chicken neck bones and hoping I get a casting area again in the future.
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How many chicken neck bones does it take for consistent 3/4” groups? Is it caliber dependent also?
:)
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Bill wrote:
"I'd then load the cases up and shoot them. I noticed that the ones that the bullet felt looser when seating did NOT shoot into the same group. It's easy to see which ones are forming a group if the group is about .6". Conversely it's easy to see which ones do not shoot into that hole.The difference was that the neck tension was not the same as the other cases. The gun had the bullets seated by hand as the chamber was an Ardito throat with matching bumped bullets."
Very interesting Bill. Do you suppose that the easily seated bullets maybe didn't have enough neck tension to firmly seat the bullet?. I can see possible mechanisms for too little neck tension or too much causing trouble. It is harder to see what the mechanism would be for variations from one shot to the next (assuming that neck tension weren't on the verge of being either too too little or too much. The forces involved are tiny compared to the force on the bullet base to accelerate it -- probably less than the variation of the gas pressure.
Bottiger tried hard to do what you just reported. He couldn't find any detrimental effect in either accuracy or velocity. I believe he also had an Ardito type set up.
I hope you will put together a fouling shot article on your tests.
John
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The cases weren't sized as they were shot in a tight neck chamber. The reason for them having less neck tension is the neck turner had warmed up enough to make the necks slightly thinner in thickness. That's the reason for the reduced neck tension.
Shooting was the “proofing” of the cases, verifying they were of good enough quality for competition.
I believe Ardito guns were tight necked guns and he may have specified a bullet diameter and a case neck thickness. The caliber is a .30BR I didn't do any tests other than a modified ladder shooting to determine the powder charges that equated to “nodes” or harmonic vibration points. From what I've heard there are three accuracy loads for any rifle with a given powder charge/bullet. A low/medium/high velocity node. Possibly there could be more but they would be beyond safe pressure limits.
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billwnr - how much of the bullet went into the case neck? Not much I'd guess. If a lot of the bullet was in the neck, then was the bullet seated off, with bullet jump?
Interesting about the warm tool - do you use a ball mic to check this?
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The way we checked about the consequence of a tool warming up was measuring the finished thickness of the neck with a ball mike.
The way we eventually worked around the tool warming up was to have some ice cubes in a baggie and sit the tool on the baggie, using it as a heat sink. It was still a variable as we were only playing with a couple of ten thousands so we limited the case neck turning exercise to about 25 cases. 20 for shooting and 5 for out of tolerance cases.
How much went into the case. Initially it was just the gas check. As it was seated the closing of the action seated it a bit deeper as the bullet and the throat mated together.
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Thanks. That makes perfect sense. And so when you seat the bullet/case in the chamber, the bullet mates the two tapers without a jump.
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=Thanks Bill, I apologize for taking so long to respond. If the bullets with less neck tension shoot out of the group I would suspect that they are being pushed back into the case further (thus reducing case capacity and raising pressures and velocity. Rounds loaded with greater neck tension will push the bullet further into the rifling and have the intended pressure and velocity, as well as seating the bullet at a different angle from the case with lower neck tension. If I am just off in the ether here please tell me so, but this theory (I have others, but they are nuttier) seems to fit the observed results. Now all we need is somebody with and extra grand ($$$$) to test it out. BrodieIf you are forcing the bullets into the lands doesn't that make neck tension kind of an moot point? I would think that it should take a great deal more pressure to overcome the friction and inertia of a land engraved bullet as opposed to overcoming any reasonable neck tension. I realize that some powders need the bullets to be tightly crimped in order to burn completely or thoroughly ( as in say the 44 mag with heavy charges of slow burning powder and light bullets for an extreme example), but if you are shooting that same combination of load in a single shot rifle would not jamming the bullet into the rifling accomplish the same thing? Does anybody know where we can get one of those pressure measuring devices that you place the sensor on the barrel and hook up to a computer. They are supposedly quite sensitive and will give you an idea of pressure differences between land engraved bullets and how much the neck tension affects pressure of not. Brodie
Not quite. The bullets will still shoot out of the group if there is not uniform neck tension or un-tension. It needs to be the same from shot to sho
The term I was looking for was PIEZOELECTRIC measuring device.
B.E.Brickey
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Potentially the bullets aren't seated in the throat as well as the cases with more neck tension If they are seated further in the case I would suspect its minute and not enough to raise pressures and velocities.
By shooting out of the group I mean there's a nice round hole for the group and one alongside say about 2/10ths of an inch away.
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Bill, I only meant that the pressure rises when a bullet is pushed back further into the case. Not that the pressure increases appreciably. Also, if neck tension is low enough for this to occur then won't the bullet be pushed out of line with the bore? Tilted if you will?
I realize that we are talking about very small amounts here not great differences in pressure or alignment, but small amounts which seem to be enough to alter the point of impact and move that shot out of the group. It is an idea to play with any way. Something to mull over on the nights when you can not sleep. Or, your wife is talking to you about something you have no interest in whatsoever. Brodie
B.E.Brickey
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Bill,
I only meant that the pressure rises when a bullet is pushed back further into the case. Not that the pressure increases appreciably. Also, if neck tension is low enough for this to occur then won't the bullet be pushed out of line with the bore? Tilted if you will?
I realize that we are talking about very small amounts here not great differences in pressure or alignment, but small amounts which seem to be enough to alter the point of impact and move that shot out of the group. It is an idea to play with any way. Something to mull over on the nights when you can not sleep. Or, your wife is talking to you about something you have no interest in whatsoever. Brodie
I am no expert, but I do think about these kinds of things strangely enough. I can't see how the bullet would be pushed out of line with the bore. I do understand what your talking about. The way I see it, whatever the neck tension is - high or low - there is still tension on the greater part of the bullet than the rest(whatever may be engaged in the throat/lands). The mechanics of how that bullet gets put into the chamber, if it is the same or close to it, would mean that the throat catches the bullet the same each time. This is predicated on whether or not the bullet is loaded in the case the same way as far as concentric goes. So as the action closes the bullet has equal pressure on all “sides” of the front of that bullet, then the neck tension would just dictate how much gets pushed back into the case or how much gets pushed into the rifling. It would take much more pressure to cant the bullet into the steel of the rifling vs the brass of the case. Even at that, the chamber and bore would have to be something bad out of line. But, if there is a lot of neck tension, then at that point the bullet would be chambered crooked only if the round or bore/chamber is not concentric. That's the way I see it, unless I am completely missing the point of what your talking about. But I am pretty sure I can see your thought on the matter.
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A few years ago I was trying to get a rifle shooting well for the nationals. I had taken care of most of the nits we have discussed in this forum the past few weeks. Everything looked good except about one shot in each ten went elsewhere. The bushing I used in my sizing die gave just enough tension to hold the bullets (.310). A jacketed bullet would slip right into the interior of a sized case. As a quick fix I started running the loaded rounds through a Lee factory crimp die. I don't usually do this with cast loads because I worry about actually resizing the bullet in the case. All I can tell you is that tightening the neck tension gave very positive results in this case. The random bullet strikes went away. In retrospect it seems likely that the bullets WERE slipping back into the case a I closed the bolt. I don't worry about neck tension to aid in ignition but you do need enough to assure that bullets engage the rifling the same each time.
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If one can find the old Ardito articles in the Fouling Shot he wrote about throating. One of his tests was how far out the rifling could be before it affected accuracy. His tests showed it didn't make much, if any difference.
If a “loose” (and I use the term loosely) neck causes a bullet to be seated further into the case as it's not being jammed (and I use that term loosely also) into the rifling, it's not more than a few thousandths deeper. The result of a looser neck should be the bullet resting on the rifling and not being seated into the rifling. That shouldn't affect accuracy at all. The looser neck should be more of a problem.
I think some of you guys are assuming the bullet is being forced back a quarter of an inch or so. This is not the case.
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