BS-Neck tension

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  • Last Post 24 August 2018
joeb33050 posted this 11 August 2018

 

Neck tension

 

There’s a test in TFS on this, John A. knows where. Neck tension affecting accuracy with < ~.75” groups may happen, but if so, the test results are well hidden.

 

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John Alexander posted this 24 August 2018

At times this thread has gotten a bit over the line with unacceptable language. I will admit that I have been a bit frustrated at times and perhaps not as patient as I could have been.  Review of some principles may help future discussions.

 

One purpose for the forum is provide for honest discussion and honest discussion will include disagreements from time to time. THAT IS OK. Different viewpoints and presenting your side of an issue if it includes presenting evidence is one way can learn and get better performance in our shooting.

 

Having someone say they believe you are wrong is NOT a valid reason to either call names,  assign undesirable character traits to the other guy, or engage on aggressive or hostile speech. Write only what you would say in a face to face conversation when the other guy is Mike Tyson.  Read what he claims and take a deep breath or a break before answering.  Asking for his evidence is appropriate and so is mustering your argument and evidence and making your best case.  Keeping an open mind to the possibility that we could be wrong is sometimes hard to do but would improve the quality of our discussions.

 

Most members including most posters have indicated that they don’t like negative bickering so please dial it back a bit and keep this forum one we can all enjoy.

 

Thanks for your cooperation.

 

John

 

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John Alexander posted this 13 August 2018

"What matters most is CONSISTENT BULLET PULL, and it matters a great deal. I can create flyers 2 or 3 inches outside of the group, on demand, with rifle calibers feom .22 to .30, simply by throwing in a cartridge that required noticeably less effort to seat the bullet."

Geargnasher

With all due respect, I think you are going to have a very hard time showing that consistent bullet pull "matters a great deal" much less "matters most".  In fact, think it is going to be hard to show that it matters at all.

I could say that in my 40+ years of experimenting with cast bullets I have never been able to show that consistent bullet pull matters one whit in the type of rifles used in CBA competition.  But that shouldn't carry any more weight than your statement that it causes huge fliers. Neither amounts to much more than anecdotal evidence without a well run experiment to back it up.

Fortunately, I don't have to do that because Gerry Bottiiger has already done it with an elaborate well designed set of experiments that showed that neck tensions that vary by near 100% had no effect of either accuracy or muzzle velocity.  In effect accepting the challenge in your post above 5 years before you made it. Gerry's article was published in TFS #223 and 224 in 2003, and no one has refuted his finding in the intervening years. His two articles can be found in the CD for Fouling Shots from 2008 - 2015 for sale at our website for $14.95. One of the advantages of being a CBA member is being able to read such articles when they are published.

If you would PM me your email address I would be happy to send you a copy of a later Fouling Shot article in which I reviewed Gerry's work and expanded on the subject -- at no cost.

John

 

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OU812 posted this 16 August 2018

more neck tension will help chamber a snug fitting bore riding bullet. not enough tension could cause bullet to slip back into case and not chamber deep enough.

I wonder what type of cast bullet Bottiger was using during his test...bore rider, taper bumped bore rider, taper bumped loverin...?

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John Alexander posted this 20 August 2018

No, John, the reason why you haven't progressed in this century is because of myopia, group think, and lack of curiosity.

Geargnasher,

That is a pretty ugly list character traits to lay on CBA shooters by a non-member who as far as I know has never had his shooting results printed in CBA match reports.  The CBA shooters I know are a pretty respectable bunch who share their knowledge freely both in TFS and on this forum. They also have the courage to show up at matches where their groups are measured by others and if their groups don’t match the results they have claimed on the internet that’s just the way it is.

Group think?? Virtually all my TFS articles are challenging the conventional wisdom about cast bullets. Please look up the meaning of "group think". 

As far as “lack of curiosity” I have offered to send you an article that that would show any open-minded person that your belief in the importance of variation in neck tension to accuracy is wrong and explain why -- all at no cost.  So far you apparently haven’t been curious enough to send your address.

==================

You and others have gone far out of your way to prove my statement "wrong".

==

That’s because it was wrong.  Having misleading claims on the forum without a rebuttal is not helpful if we are going to learn anything. If you didn’t agree, an intelligent response would have been to submit evidence that you were right, not attack the character of those who disagree with you.

Learning is the major reason the CBA offers this forum.  If enough open-minded shooters participate we will all learn things we didn’t know. It is not a place for grand claims that aren’t verified and can’t be questioned.  If you don’t like others disagreeing with you and citing evidence you are wrong, you are in the wrong place.

I'm tired of your resistance to learning, so have fun doing it the same old way and I'll get back to more productive endeavors.

While you are looking up group-think you may want to check out “irony” as well.

John

 

 

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shootcast posted this 21 August 2018

I don’t shoot as well but have experimented with neck tension. Jerry’s artical took a great deal of tIme experimenting. One thing I would add I have read in reloading manuals. Since neck tension can be from a slip fit to a rather tight force the powder used can have a effect. Jerry test was with one powder and one bulletin and one firearm. My test showed loose necks and fast powders are better than loose necks and slow powders. To each there own but after lots of trial and error I believe you need enough to hold the bullet firmly but not excessively.

 

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Shopdog posted this 21 August 2018

Probably shouldn't respond,oh well....

Don't confuse,... tension.... friction(seating).... hold.

K&M,21st century and some other co( CRS) has been making bullet seating force gauge equipment for a loooong time. It's been pretty well documented in long range JB shooting that batching rounds with very low ES on these gauges shows up on paper.

Just an observation, what gets this discussion derailed is..... does a bullet move forward at the moment of ignition.... OR ..... case neck expands cutting all bullet to case "ties" free. Solve this,and it may help show what once held dear,may not represent the full spectrum of engineering available at any one point.

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OU812 posted this 21 August 2018

I can see why neck tension would not matter when shooting cast bullets because the bullet should always be chambered to stop against the throat. This resistance makes neck tension null. 

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John Alexander posted this 22 August 2018

Question 2. Will the shot to shot variation in neck tension affect accuracy or muzzle velocity? This was the question I thought this thread was about because of the first two posts. This question has been answered and the answer is no, it doesn’t affect accuracy or muzzle velocity (at least until someone does the research to prove otherwise.) Then why do cartridges with a bullet that was harder to seat usually shoot out of the group? I've seen that quite a bit and remove those from the lot.

============

45.2.1

A bullet very hard to seat may be damaged or set back during seating. I would suggest that you examine your reloading methods and find out why you would have a bullet extremely hard to seat. Proper loading practices should eliminate such inconsistency.  I have never seen a systematic test that shows what you claim is really true but one very good one that shows that it isn’t true. Anecdotes like yours, if repeated often enough, sometimes become the conventional wisdom but that doesn’t make them true.

==========

Aside from Bottiger's excellent work I haven't seen you say exactly what he was doing for a proof.... can you quantify exactly what he did for all of us since you say it's true? Some proof, not speculation since you made a definitive statement on the matter?  

===========

I outlined what he did for proof in the fifth post in this thread.

I suggest you read that post and read the article. Then try to understand what you have read before asking more preachy and insulting questions. 

============

Rationalizing is not proof. If it is true, then a scientific or mathematical analysis should be shown .

“Rationalizing” doesn’t make any sense used in that sentence.  Please look the word up. Why are you accusing Bottiger of “speculation” and “rationalizing” any way when you haven’t read the article? 

Any shot to shot variation in the tiny force that neck tension could possibly provide will be overwhelmed by the much, much, larger variation in the force doing the pushing. As a math major might say "it is in the round off error and insignificant. 

As an engineer, I've found rounding gives an imprecise answer in real world situations and can cost big money to correct. Hard concrete numbers are hard to argue with...... Math has proofs for assumptions.... until proven with hard numbers, they are just assumptions.

Both of the sentences in that statement are incoherent and basically baloney.  But they do reveal a complete ignorance of the role in rounding off and respect for significant figures in engineering calculations. I don’t know what engineering school you went to, but you wouldn’t have made it through one of my classes without a better understanding of the proper use of rounding off and significant figures for displaying a realistic level of precision in engineering calculations.

John

 

 

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joeb33050 posted this 24 August 2018

One purpose for the forum is provide for honest discussion and honest discussion will include disagreements from time to time. THAT IS OK. Different viewpoints and presenting your side of an issue if it includes presenting evidence is one way can learn and get better performance in our shooting.

If people discuss their favorite color, mine is blue, these are opinions.

Discussing the value of pi, the fact that velocity is a vector quantity, or the mating habits of blue whales serves no purpose. Opinions don't matter.

If we want to know if it is raining out, forming a committee to analyze and discuss the question is beaten by looking out the farking window.

Will bullets without  lube lead the barrel? Will they shoot accurately? 

Experiment, get some DATA, stop the nonsense!

 

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Geargnasher posted this 12 August 2018

What matters most is CONSISTENT BULLET PULL, and it matters a great deal. I can create flyers 2 or 3 inches outside of the group, on demand, with rifle calibers feom .22 to .30, simply by throwing in a cartridge that required noticeably less effort to seat the bullet.

That said, the inconsistency is relative to POI, not necessarily to group size. Sorted by seating effort, it is possible to shoot several equal, or nearly equal, groups with different points of impact.

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joeb33050 posted this 12 August 2018

What matters most is CONSISTENT BULLET PULL, and it matters a great deal. I can create flyers 2 or 3 inches outside of the group, on demand, with rifle calibers feom .22 to .30, simply by throwing in a cartridge that required noticeably less effort to seat the bullet. That said, the inconsistency is relative to POI, not necessarily to group size. Sorted by seating effort, it is possible to shoot several equal, or nearly equal, groups with different points of impact.
YOU DIDN'T READ THE ARTICLE. WRITE ONE, YOU SEEM TO HAVE A LOTTA OPINIONS. ANY Data?

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Geargnasher posted this 12 August 2018

I don't have access to the article, and am responding to your BS topic in general with the conclusions of 25 years of my data. Anyone can easily duplicate it.

If you don't believe me, prove it wrong, with your own tests.

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Ken Campbell Iowa posted this 14 August 2018

my obsessive mj benchrest buddies assure me that the brass neck expands before the bullet moves much ... and so i have this mental image of ....

at the shot the tight or loose neck tension doesn't count anymore... and the bullet is just left there, in mid-air ... free to flop or twist however the gases push it .... 

so maybe we should make the turned neck a very tight fit in the chamber :::   same od as the chamber neck id ... the case neck at firing does guide the bullet .... almost like a breech-seated bullet ........ ( dangerous? ... probably not with lead bullets and loads worked up with this arrangement in mind . )

***************

the above is a recurring mental image i harbor .... not sure if it has merit ... but after i get some other projects done i am betting a match barrel and about 3 days of shop time on it.  probably 6mm ....  what could go worng ?

ken  

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pat i. posted this 14 August 2018

I think Dave Lee and maybe a few other guys out west did or do use an interference fit like you're describing. I could be wrong but don't think so and if they did/do you can't deny the results.

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John Alexander posted this 14 August 2018

Bob Birmley's fairly recent articles on "Going for Records or some such title talks of this method. One part of the article that I don't disagree with.  And Pat is right. Dave Lee and his disciples were hard to beat and still hold records.

John

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Larry Gibson posted this 15 August 2018

I prefer to use .002 - .003 neck tension simply because it holds the GC'd bullets securely in the case neck. I've not found that neck tension alone can be attributed to accuracy enhancement.  I have found that too much neck tension can cause damage to the bullet during seating, especially PB'd cast bullets of softer alloy, during seating by swaging the bullet down and causing damage to the nose from the seating stem.  Also too much neck tension with GC'd bullets can cause excessive run out as the GC expands the case neck.

Sizing to minimal .002 - .003 tension also reduces the working of the case necks giving longer case life and more firings before annealing may become necessary.  I used bushing or collet dies and proper size expanders in M dies to achieve that amount of neck tension.

LMG  

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

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John Alexander posted this 15 August 2018

Larry is right, of course, there are all kinds of ways that the WRONG NECK TENSION can cause all kinds of problems both to little and too much neck tension.

Gearnasher's statement was that shot to shot VARIATION in neck tension was very important. Bottiger's research with a combination averaging very close to .5 MOA has blown that claim out of the water.

The most interesting thing about variation in neck tension is that people continue to think it is important in spite of it being debunked as completely as it could possibly be. No wonder we haven't progressed in this century.

John

 

 

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Ken Campbell Iowa posted this 15 August 2018

... i find it interesting that in mj benchrest ... some midwest top shooters are working with a cartridge ... that has almost no neck at all ...... and are doing very well with it ...  this might be worth a go in cast shooting ...  the idea is that the case is located by pushing the tapered shoulder against the tapered front chamber  ... and then we can get creative with the freebore and throat..... mainly make it very snug .....

kinda like the often botched effort to push a tapered bullet against a tapered throat.  while better than a straight throat in theory .... there really isn't a lot of rifling to taper .... 1 degree per side only grabs about a quarter inch of the bullet ...

i need one of those " limitless " brain pills to consider the ramifications of a neckless case ...  but worth a mild migrain i spose ...

ken

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pat i. posted this 15 August 2018

I wonder if after a couple of thousandths adding more tension does anything at all. The bullet acts as an expander so everything after what's required to grip it might be wasted effort.

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joeb33050 posted this 16 August 2018

I don't see any change in mv or accuracy with varying neck tension; and I don't understand why neck tension is measured in thousandths of an inch. If a set of cases is neck sized and then pushed in/out of an M die, there is a wide variation in force required to get the neck on and off the spud. Diameter AND hardness of the neck combine to determine the force required at the M die. This with necks brushe3d.  Neck turning and annealing may reduce the variation. I have had instances of seating a long bullet where the seating bumped up the shoulder/body area, changing bolt closing force.

 

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