Case neck tension - what a difference [Archive] - Glock Talk

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PCJim
08-19-2012, 20:37
I decided to finish loading up some 308 precision rounds this weekend that I had begun working on several weeks ago. 80 cases were Federal that were previously fired in my SPS that were neck sized only; 15 cases were RPU that were FL sized that I wanted to run as an experiment (how much of a group difference would they make as compared to the cases previously fired thru the SPS).

What I found while loading the 168gr SMKs was that there was a very noticable difference in the neck tension between the FL and neck-only sized cases. The neck sized cases (Lee collet die) had just barely enough tension to hold the bullets - adequate, but not nearly as tight as the FL sized cases (RCBS).

This should add some additional insight on how these neck sized rounds shoot. The cases previously fired in the SPS were new Federal brass that was initially prepped by FL sizing during the loading. They were able to give me a five shot .583 grouping (100yds) during load development.

:shocked: I know Steve is going to jump in here and offer up that I should have taken multiple ID and OD measurements. I now think that doing so could have been rather informative. Maybe I'll go out and take some readings on other once-shot brass later on tonight.

Has anyone else noticed any differences in neck tension between neck sizing dies and FL dies?

Colorado4Wheel
08-19-2012, 21:01
www.6mmbr.com/catalog/item/1433308/1464783.htm

Colorado4Wheel
08-19-2012, 21:06
Just to be accurate it's I.D. that you want as well.

steve4102
08-20-2012, 05:56
The neck sized cases (Lee collet die) had just barely enough tension to hold the bullets - adequate, but not nearly as tight as the FL sized cases (RCBS).

Lee sets up the Mandrel size for approximately .001 neck tension. I polish my mandrels down to increase neck tension on all my Collet dies. You can also order a Reduced mandrel directly from Lee.

Hoser
08-20-2012, 06:49
Neck tension is tricky. For single shot rifles .002-3 is plenty. Mag fed rifles need a little more.

However what matters is downrange results and a low ES and SD across the chrono. Sometimes more neck tension will bring down the ES/SD.

At short to mid range it isnt a big deal. Past 600 yards, big deal.

fredj338
08-20-2012, 09:10
Lee sets up the Mandrel size for approximately .001 neck tension. I polish my mandrels down to increase neck tension on all my Collet dies. You can also order a Reduced mandrel directly from Lee.

^^THIS^^ I Only have one set of the Lee neck dies, but found the neck tension not to my liking so ploished the mandrel down.

PCJim
08-20-2012, 11:47
If the wind lays down enough this upcomming weekend to shoot these rounds, I'll post the results. If the neck sized brass doesn't deliver similar results to those obtained during load development, I'll consider polishing the mandrel down a bit.

squirreld
08-20-2012, 21:15
How do you polish down a carbide button expander ball?

steve4102
08-21-2012, 06:40
How do you polish down a carbide button expander ball?

Duno. The Lee Collet die is nether carbide or an expander ball. It is a steel mandrel that can be reduced or polished down by chucking it into a drill and polished with fine emery cloth.

WiskyT
08-21-2012, 08:05
Lee collet die: I am not a "rifleman". I haven't loaded much more than a few hundred 30-06 rounds and they all have been with the Lee collet die. When I started out, I was using a Lee hand press. I had some rounds with very low neck tension. I didn't measure it with instruments, but it was obvious that there wasn't enough tension as some bullets slid into the cases.

Since I switched to using the same dies, same brass, same bullets, and same rifle, with my RCBS Junior press, I no longer get any neck tension issues. The reason is I'm able to apply much more pressure on the collet. The Lee instructions understate the ammount of pressure needed to size the neck properly. You really need to bare down on the thing to make it work. Adjust the die body down a bit further so you really cam over on the linkage and it should work fine.

Dressing the mandrel down might work as well or better, I haven't tried it. First I would try adjusting the die body down and see how it works as I always try the easy solutions, especially ones that don't alter equipment, first.

fredj338
08-21-2012, 13:21
How do you polish down a carbide button expander ball?

You would need special diamond grinding setup. As noted, doesn't matter as the Lee is just steel.
Adjusting the die down may work, but go too far & you crush cases. Don't ask how I know.

WiskyT
08-21-2012, 15:16
You would need special diamond grinding setup. As noted, doesn't matter as the Lee is just steel.
Adjusting the die down may work, but go too far & you crush cases. Don't ask how I know.

You crushed a case with a Lee collet die?

Boxerglocker
08-21-2012, 18:04
I need to experiment with my Lee 223 collet die. I ordered some Lapua brass, after I form fire it I will neck size only.
I also heard that moving the die too far down will crush the shoulder. So Fred polishing the mandrel down... how much, 0.002?

fredj338
08-21-2012, 23:29
You crushed a case with a Lee collet die?

Oh yeah, easy to do. Just screw the die in too far.:wow: The whole case doesn't crush but the neck/shoulder does.
Polsihing down as little as 0.0005" is enough for most brass, 0.002" is actually quite a lot.

WiskyT
08-22-2012, 07:01
Oh yeah, easy to do. Just screw the die in too far.:wow: The whole case doesn't crush but the neck/shoulder does.
Polsihing down as little as 0.0005" is enough for most brass, 0.002" is actually quite a lot.

I'll have to keep on my toes regarding that.

As for how much tension, I'll leave that to you and Hozer etc, guys who have tired different levels of tension and seen the results. According to Lee, any more than 0.001" is wasted because the brass stretches anway. His instructions are geared to "normal" reloading though, and not precision shooting.

Maybe I will polish my mandrel down a lrch next time I use it. It sounds easier than bearing down on my press and hoping something doesn't pop or a shoulder collapse.

Boxerglocker
08-22-2012, 08:04
This guy had some good insights. I took his suggestion of polishing down the collet bevel to smooth it out and using a touch of lithium grease. I polished the mandrel down another 0.0005 and give it a once over with flitz.
Experimented a little with some brass and got it adjusted to my liking. I'll have to check measurements when I get my Lapua brass.

http://youtu.be/mhTUgytUGnM

Colorado4Wheel
08-22-2012, 10:14
If you read that link I posted a couple post back you will see others have found brass spring back to be in the .002-.003 " range. Lee seems to think brass has very little spring back. Others seem to think it has more. My measurements show it to be WAY more then .001" (which is not a lot). To me it's pretty obvious that brass sized .001" under the bullet size has way less neck tension then a case sized .002" under bullet size. Others in this thread seem to agree.

Basically, Lee is wrong on this and he drives me nuts.. :rofl:

I just had to say it.

Carry on. :wavey:

Hoser
08-22-2012, 10:19
Best fix is to just get Redding or Forster bushing dies and go to work.

The whole polishing down a mandrel thing to get the right size seems like a lot more work than it needs to be.

WiskyT
08-22-2012, 10:34
If you read that link I posted a couple post back you will see others have found brass spring back to be in the .002-.003 " range. Lee seems to think brass has very little spring back. Others seem to think it has more. My measurements show it to be WAY more then .001" (which is not a lot). To me it's pretty obvious that brass sized .001" under the bullet size has way less neck tension then a case sized .002" under bullet size. Others in this thread seem to agree.

Basically, Lee is wrong on this and he drives me nuts.. :rofl:

I just had to say it.

Carry on. :wavey:

Uh, that' not what Lee is saying. He's not talking about spring back. He's talking about no matter how small you make the ID, it will stretch with the insertion of the bullet so that it is no more effective than if it had been 0.001" undersized to begin with.

He's not saying if you squeeze it to 0.305" it will bounce back to 0.306", what he's saying is if you size it to 0.305", or 0.307", it will not grip the bullet any more firmly.

WiskyT
08-22-2012, 10:40
Best fix is to just get Redding or Forster bushing dies and go to work.

The whole polishing down a mandrel thing to get the right size seems like a lot more work than it needs to be.

It depends on what you want to do. For $20.00, I have a die that makes ammo with a load that I picked out of a Hornady manual that shoots 0.75MOA out of a $250.00 Stevens I bought on clearance at Dick's.

My die works fine as is. It worked well overall with an occasional glitch until I learned how to use it properly. I'm fence sitting as to whether I want to spin the mandrel in a drill and polish it with a Scotchpad.

Some Palma match guy or whatever (1000 yard) held the world's record for a few years using the Lee collet die. If it's good enough for him, it's good enough for me.

Boxerglocker
08-22-2012, 11:54
If you read that link I posted a couple post back you will see others have found brass spring back to be in the .002-.003 " range. Lee seems to think brass has very little spring back. Others seem to think it has more. My measurements show it to be WAY more then .001" (which is not a lot). To me it's pretty obvious that brass sized .001" under the bullet size has way less neck tension then a case sized .002" under bullet size. Others in this thread seem to agree.

Basically, Lee is wrong on this and he drives me nuts.. :rofl:

I just had to say it.

Carry on. :wavey:

I think the question is how does the actual neck tension affect the performance of a otherwise optimized precision load? I personally feel 0.002 should be minimum for a bolt action load. I measured a couple of FL dies that I have Dillon and RCBS) with LC brass and got sizing to the 0.008 range.
That being said until now all my .223 brass was FL sized with Dillon dies and I have a few proven sub half MOA loads.
I'm taking Hozers warning that at 500-600 it all makes a difference though so threading carefully to not waste time or energy.

Boxerglocker
08-22-2012, 11:57
Uh, that' not what Lee is saying. He's not talking about spring back. He's talking about no matter how small you make the ID, it will stretch with the insertion of the bullet so that it is no more effective than if it had been 0.001" undersized to begin with.

He's not saying if you squeeze it to 0.305" it will bounce back to 0.306", what he's saying is if you size it to 0.305", or 0.307", it will not grip the bullet any more firmly.

That's the way I read it too. It's metal ductility... in fact you will most like lose tension if you over under size to 0.003 and back to 0.001 when a bullet is inserted.

F106 Fan
08-22-2012, 12:14
Re: the idea that bullet tension isn't related to neck size (0.002" vs 0.004" for example), I wonder if it would be possible to measure the hande effort required to seat the bullet with a trigger gauge? For that matter, maybe there is a way so clamp something on the bullet and directly measure the force required to pull the bullet. Just for giggles, since I don't believe for a moment that there is no difference.

Once the neck is sized, that is its natural diameter, whatever it is. When the bullet is seated, the elastic nature of the brass is allowing the neck to expand. To the extent that we don't exceed the elastic limit, increasing the expansion will increase the tension. At least this seems a reasonable explanation. But it should be easy to measure!

There is one theory for precision rifle that suggests the neck tension be sufficient to be capable of ejecting a loaded round without leaving the bullet behind. The test case would be the situation where the bullet is deliberately impacting the rifling. In fact, some folks load a little long with the intent that the bullet will be set back during chambering. So, this group doesn't want much neck tension. Perhaps 0.002" is enough. I don't have my paperwork in front of me but I think that is what I am doing with my Redding neck sizing die for the 6.5x284 Norma. The only difference is that I can't get within 0.060" of the rifling before the bullet falls out of the case. Savage made a very long chamber.

If the Dillon sizing die creates 0.008" tension, that seems great for autoloaders. We really don't want the bullet moving around on AR-15s. In fact, the Montana Gold 55 gr has a cannelure so I am adding a little crimp with the Lee FCD. I want the bullet to stay put!

Richard

Colorado4Wheel
08-22-2012, 12:26
Uh, that' not what Lee is saying. He's not talking about spring back. He's talking about no matter how small you make the ID, it will stretch with the insertion of the bullet so that it is no more effective than if it had been 0.001" undersized to begin with.

He's not saying if you squeeze it to 0.305" it will bounce back to 0.306", what he's saying is if you size it to 0.305", or 0.307", it will not grip the bullet any more firmly.

And that is not true. If you size .001" undersize vs .003 under the size of the bullet the one sized more will have more bullet tension. We all know that. I have seen that in my Lee .380 dies that size just barely undersize and don't grip the bullet well at all and if you get one (that they sell) that is another .001" undersized beyond their standard it will actually grip the bullet better and pass the basic "push it on the bench test" that we all use.

Basically. He is wrong.

Colorado4Wheel
08-22-2012, 12:28
That's the way I read it too. It's metal ductility... in fact you will most like lose tension if you over under size to 0.003 and back to 0.001 when a bullet is inserted.


There is a point of diminishing returns. No doubt about that. And it does vary based on the bullet/case neck size. Bigger is more ductile then smaller.

WiskyT
08-22-2012, 14:29
And that is not true. If you size .001" undersize vs .003 under the size of the bullet the one sized more will have more bullet tension. We all know that. I have seen that in my Lee .380 dies that size just barely undersize and don't grip the bullet well at all and if you get one (that they sell) that is another .001" undersized beyond their standard it will actually grip the bullet better and pass the basic "push it on the bench test" that we all use.

Basically. He is wrong.

Well, there is your anecdotal approach, and then there is Lee's engineering approach. There is so much more to this that you could never measure with a caliper that for you to even guess at this is not worth the effort. Metals have yield points. Yield points are effected by the alloy used, the heat treating, the work hardening, the amount of times they are over worked before re-heat treating, the amount that the brass gets hardened from the working of it based on how hot the loads are, how large the chamber is. There is the lubricity of the brass and what is stuck on it, the lubricity of the bullet and what is left on it during the manufacturing process.

Really, for all the people wearing out micrometers on this stuff, has anybody bothered to make sure there is a consistent level of dirt, oil, carbon etc on the inside of the neck and the bullet? Do you check the ID of every neck every time you reload it? Unless you do, it's all a crap shoot anyway. You'd also have to check the ductility of the neck, probably through some kind of destructive testing at a materials lab, every time you reload it.

Maybe Hozer has since his type of shooting probably requires that stuff.

As for a basic guideline that 0.001" interference fit is the limit for neck tension, it works for me. My spire point fmj 06 rounds dent my bench without set back on brass that's been loaded prolly 4 times without annealing. Maybe in four more loadings they will start to slip and I'll have to anneal them?

WiskyT
08-22-2012, 14:43
http://www.accurateshooter.com/technical-articles/reloading/neck-tension-not-just-bushing-size/

Boxerglocker
08-22-2012, 15:49
Well, there is your anecdotal approach, and then there is Lee's engineering approach. There is so much more to this that you could never measure with a caliper that for you to even guess at this is not worth the effort. Metals have yield points. Yield points are effected by the alloy used, the heat treating, the work hardening, the amount of times they are over worked before re-heat treating, the amount that the brass gets hardened from the working of it based on how hot the loads are, how large the chamber is. There is the lubricity of the brass and what is stuck on it, the lubricity of the bullet and what is left on it during the manufacturing process.

Really, for all the people wearing out micrometers on this stuff, has anybody bothered to make sure there is a consistent level of dirt, oil, carbon etc on the inside of the neck and the bullet? Do you check the ID of every neck every time you reload it? Unless you do, it's all a crap shoot anyway. You'd also have to check the ductility of the neck, probably through some kind of destructive testing at a materials lab, every time you reload it.

Maybe Hozer has since his type of shooting probably requires that stuff.

As for a basic guideline that 0.001" interference fit is the limit for neck tension, it works for me. My spire point fmj 06 rounds dent my bench without set back on brass that's been loaded prolly 4 times without annealing. Maybe in four more loadings they will start to slip and I'll have to anneal them?

It's just a matter of consistency, knowing where you are in the beginning makes it easier to find your way home when you get lost. In the case of precision rifle loading, it's gives you variables on what you can adjust or improve.
You mention your dent check on you bench for setback test.
If you apply a 0.008 vs a 0.001 on cases with a applied for of 35#s by your hand will have the deepest dent? You don't know, right? Especially if they never slip? You need to have know variables if you wish to make improvements. I think that is all Steve is bringing to light and I for one agree in this case.

PCJim
08-22-2012, 16:07
Lee collet v Redding bushing dies... I read somewhere (yes, I know, but that's why I went with the Lee) that the collet die was preferred for the fact that, by design, the brass case is self-centering inside the die. That makes sense to me as a layman. Maybe I should look for that article. I haven't seen the innards of the Redding bushing die so I can't speak for it.

I would have to agree that a case mouth undersized by .003 would have much more purchase on a bullet than one undersized by .001. Both get stretched to accommodate the bullet.

Some of the loads I made might not pass the benchtop test. I haven't had the time or inclination to get back in front of the bench since the weekend, so will test a couple when I do. AND, I now have Isaac wanting to come acalling when he really hasn't been invited. At least I can say that he gives adequate notice.

fredj338
08-22-2012, 16:37
If you read that link I posted a couple post back you will see others have found brass spring back to be in the .002-.003 " range. Lee seems to think brass has very little spring back. Others seem to think it has more. My measurements show it to be WAY more then .001" (which is not a lot). To me it's pretty obvious that brass sized .001" under the bullet size has way less neck tension then a case sized .002" under bullet size. Others in this thread seem to agree.

Basically, Lee is wrong on this and he drives me nuts.. :rofl:

I just had to say it.

Carry on. :wavey:
And that wil change the more times the case is fired.:dunno:

WiskyT
08-22-2012, 17:52
It's just a matter of consistency, knowing where you are in the beginning makes it easier to find your way home when you get lost. In the case of precision rifle loading, it's gives you variables on what you can adjust or improve.
You mention your dent check on you bench for setback test.
If you apply a 0.008 vs a 0.001 on cases with a applied for of 35#s by your hand will have the deepest dent? You don't know, right? Especially if they never slip? You need to have know variables if you wish to make improvements. I think that is all Steve is bringing to light and I for one agree in this case.

Steve's point is valid in that there is more to the picture than Lee talks about. But, Lee isn't "wrong" as Steve proclaims any more than your owner's manual is wrong when it tells you to use SAE/API motor oil of the proper viscosity. Sure, does Honda off-road racing team use different oil or additives? Of course they do. Does that mean the manual is wrong to tell you to use SAE5W30 and leave it at that?

And there is going to be a limit to interference fit. Where that is I don't know. But you can't go by intuition because intuition tells you that more is better and there is a point where it isn't.

Think about a nut and bolt. Show the average person a 1/4" bolt and a 1/4" thick nut. Then show then a 1/4" nut that is 1" deep (if you can find one). Ask them which nut will be stronger in terms of tensile strength and the average person will always pick the deeper nut. The correct answer is that they are both the same. The limit for a female threaded part is the diameter of the male piece that fits into it. Any longer is superfluous.

It's the same with neck tension. There is a point where more doesn't give you any better grip. Lee says it's 0.001". I'm inclined to believe him because he looks at these things from an engineering standpoint. His advice is also geared towards the majority of shooters who need ammo to function. He can't put all of Hozer's experience and knowledge into the die instructions.

n2extrm
08-22-2012, 19:10
I use the redding bushing dies. I can tell you first hand that the size of the bushing matters a lot. I have different bushings for different lots of brass. In my .308 brass the lake city stuff is much thicker and requires a much larger bushing then the Hornady match brass. If I use the bushing from the LC brass on the Hornady brass, I can seat and pull the bullets with my fingers. If you go the other way you can see e boat tail of the bullet in the neck. The results are even made worse when you start to move the bullet into the lands and you have a lot less of the bullet in the neck. So one size does not fit all.

The other side that no one is talking about is brass life. The more you work it the shorter it gets. So if you squeeze it .010 under and stretch it back out .009 every time vs getting it .002 under you hurt the brass life more.

I don't believe I can shot so well that the neck tension is going to make a huge difference but I have found it can help a bit. And the more things you can keep equal,the better.

Boxerglocker
08-22-2012, 19:49
Steve's point is valid in that there is more to the picture than Lee talks about. But, Lee isn't "wrong" as Steve proclaims any more than your owner's manual is wrong when it tells you to use SAE/API motor oil of the proper viscosity. Sure, does Honda off-road racing team use different oil or additives? Of course they do. Does that mean the manual is wrong to tell you to use SAE5W30 and leave it at that?

And there is going to be a limit to interference fit. Where that is I don't know. But you can't go by intuition because intuition tells you that more is better and there is a point where it isn't.

Think about a nut and bolt. Show the average person a 1/4" bolt and a 1/4" thick nut. Then show then a 1/4" nut that is 1" deep (if you can find one). Ask them which nut will be stronger in terms of tensile strength and the average person will always pick the deeper nut. The correct answer is that they are both the same. The limit for a female threaded part is the diameter of the male piece that fits into it. Any longer is superfluous.

It's the same with neck tension. There is a point where more doesn't give you any better grip. Lee says it's 0.001". I'm inclined to believe him because he looks at these things from an engineering standpoint. His advice is also geared towards the majority of shooters who need ammo to function. He can't put all of Hozer's experience and knowledge into the die instructions.

Point taken and understood. This is why I see GTR as the best reloading site there is period. Many aspects from different viewpoints. You can always feel free to ask a question that will be answered respectfully and intelligently, regarding the direction you want to dwell.

WiskyT
08-22-2012, 19:54
Point taken and understood. This is why I see GTR as the best reloading site there is period. Many aspects from different viewpoints. You can always feel free to ask a question that will be answered respectfully and intelligently, regarding the direction you want to dwell.

Do you? Do you really? Isn't there a part of you, deep down inside, or maybe right up there on the surface, that wishes Jack was here to goof on Stevie for using his micrometer and to point out the inherent accuracy of weapons and projectiles that not only forgo the use of cases completely, but are manufactured by a man who runs the livery stable and produces said weapons with an anvil and a coal fired furnace?

Boxerglocker
08-22-2012, 21:28
Do you? Do you really? Isn't there a part of you, deep down inside, or maybe right up there on the surface, that wishes Jack was here to goof on Stevie for using his micrometer and to point out the inherent accuracy of weapons and projectiles that not only forgo the use of cases completely, but are manufactured by a man who runs the livery stable and produces said weapons with an anvil and a coal fired furnace?

OH yeah without a doubt... but fun in learning is what makes it stick in your brain right? :rofl:

PCJim
08-22-2012, 21:40
I'm so tired of the media hype for a storm that "may" now be a direct hit and "may" be a Cat 1. Can you believe a special 30 min segment on hurricane preparedness for this little blow? So I set the glass of red down, got off the couch and finished seating the remaining thirty rounds.

Before seating, I took some measurements for Squeaker's benefit. Case mouths were sized from .304 to .307. Most already finished rounds passed the benchtop test. One of the new rounds tonight did not. That round was disassembled and reloaded.

I did segregate, by feel, those rounds tonight that had very little resistance during bullet seating. When this blow passes and I get some time to fire these rounds, I'll be able to determine whether the neck tension makes any difference in MY rifle with my skills at a measily 100yds. As always, what works in my rifle does not necessarily convey to another rifle.

Hoser
08-23-2012, 07:51
I wonder if it would be possible to measure the hande effort required to seat the bullet with a trigger gauge?

Not quite a trigger pull gauge, but...

I have a KKM arbor press, but never felt the need to get the indicator option.

http://www.kmshooting.com/catalog/arbor-press/arbor-press-with-force-measurement-option.html

Colorado4Wheel
08-23-2012, 10:03
You guys joke but I don't measure that stuff. Totally not worth it. BUT, when I had a .380 die sent to me by a GTR member we did go through the process of measure the stuff. The smaller die does add more tension and avoid bullet set back. So yeah, I have actually gone through the process of knowing what happens. It's not a guess.

WiskyT
08-23-2012, 11:36
You guys joke but I don't measure that stuff. Totally not worth it. BUT, when I had a .380 die sent to me by a GTR member we did go through the process of measure the stuff. The smaller die does add more tension and avoid bullet set back. So yeah, I have actually gone through the process of knowing what happens. It's not a guess.

You had not enough neck tension. You're saying you had a 0.001" interference fit and the bullets set back? Or you likely had less than that?

Colorado4Wheel
08-23-2012, 12:05
Nope.

Me and my machinist friend measure it.

F106 Fan
08-23-2012, 12:36
Not quite a trigger pull gauge, but...

I have a KKM arbor press, but never felt the need to get the indicator option.

http://www.kmshooting.com/catalog/arbor-press/arbor-press-with-force-measurement-option.html


That's neat! Thanks for the link.

I don't know that I shoot well enough to need such a tool but it might get on my 'want' list anyway.

Richard

WiskyT
08-23-2012, 19:48
Nope.

Me and my machinist friend measure it.

Nope what?

squirreld
08-23-2012, 20:44
I'm at about .004 neck tension on my 556 loads.
Using a Redding FL sizer with the carbide expander ball.