Question on neck tension

[Hook Creek]

Did a test today on a .308 for poi change with new and used brass on a fl die, half with expander ball, and half without found here . One thing I realized is that when sizing without the expander ball the inside of the neck measured .295, and with the expander ball it measured .300. If you read the link I posted you will see that at 200y there was no difference in POI. Is .295 too much neck tension to be seating bullets into? I would rather not use the expander ball cause its a pain in the ass forcing cases through it. I read somewhere on here that brass doesn't allow more than a .3 tension, but I feel like trying to seat the bullet when its at .295 might ruin the bullet going in.

 

[BuzzBoss915]

Re: Question on neck tension

Sounds like reinventing the wheel? Bushing dies have a very specific purpose and an expander ball has a legitimate purpose, as well. BB

 

[flashhole]

Re: Question on neck tension

You may not see any problem loading boat-tail bullets but a flat base bullet could damage the neck or shave bullets going in. You really don't want the bullet doing the dies job expanding the neck to the proper size. Hard to say how much actual force (neck tension) will be applied to the bullet or if you will see a performance difference. You would not be the first person to hone out the inside of the neck area on the sizing die if you consider going that route. It's like a bushing die with a permanent bushing.

 

[wilecoyote]

Re: Question on neck tension

if you are really interested about it,forget the expander ball: remove it from your die,trash it and buy a proper Sinclair Generation II expander die_ If you are not satisfied with the size of the inserts(selled separately), you can replace them with other, of the needed size, easily obtained with turning on a lathe your "custom" expanders_They are cylindrical,really easy to make_

 

[memilanuk]

Re: Question on neck tension

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">is .295 too much neck tension to be seating bullets into?</div></div>

Holy hell. That's way too tight!

Most .30 cal expanders (both expander plugs, balls or stems) I've ever measured mike out @ .306 or so. 2-3 thou neck tension on loaded rounds is *plenty* unless you plan on stabbing someone to death with 'em

More seriously... a little more might not be a bad thing for a gas gun or ammo you *know* is going to get handled roughly. Otherwise... I stand by the above.

I disagree somewhat with wilecoyote... a bushing die with the right sized bushing and either a polished or (preferably) floating carbide expander ball will not cause any ill effects. By 'right sized' I mean one sized so that the expander ball just *barely* kisses the inside of the neck on the way back out. That way you're not over-working the necks (which at .295 you most assuredly are), and not getting any 'drag' on the expander ball that could screw up the necks - or headspace.

Come to think of it... you'd have to be leaning on the press handle to seat a bullet into a hole that under-sized. I hate to ask... but are you sure you're measuring it right? What I mean is that some calipers have thicker blades for the ID measurement, without much bevel to them. I have a pair like that around here somewhere. It is *much* harder to get a good read on the inside of a case neck than with my 'better' calipers (Mitutuoyo Digimatic - spendy but worth it).

HTH,

Monte

 

[Innovative]

Re: Question on neck tension

Spend a few extra bucks, and get a FL "bushing" die from Redding, RCBS or Forster. The whole idea of having diffenert size buchings is to control neck tension.

That also allows you to shoot a different brand of brass that usually has a different neck thickness. Your chamber clearance will be more consistent, and your case run-out will be less than craming your case into a tight conventional die.

 

[Deadshot2]

Re: Question on neck tension

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cronos</div><div class="ubbcode-body"> I read somewhere on here that brass doesn't allow more than a .3 tension, but I feel like trying to seat the bullet when its at .295 might ruin the bullet going in. </div></div>

If you read what Richard Lee has to say on the topic, at some point the bullet becomes the expander. The case neck is expanded to the point where there will be no more actual neck tension than if you used an expander to set the initial neck tension at .003". The difference in using a ball or expander die versus the bullet is that the bullet will more likely be damaged in the expanding process. Either through shaving of jacket metal or damage at the point the seater plug contacts the bullet.

I've stopped using sizing die expander "balls" totally. Instead I elect to use a Sinclair Expander Die and expand as a separate action. When using bushing dies with neck turned cases it's merely a matter of insuring consistency because with the proper bushing I should have .002" of neck tension anyway, even before running through the expander die.

 

[MitchAlsup]

Re: Question on neck tension

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Deadshot2</div><div class="ubbcode-body">

If you read what Richard Lee has to say on the topic, at some point the bullet becomes the expander. The case neck is expanded to the point where there will be no more actual neck tension than if you used an expander to set the initial neck tension at .003". </div></div>

Correct, the neck can only hold 48K PSI of neck tension (not PSI form rather than 0.00x form). If a bullet is inserted into the neck that creates more than 48K PSI of neck tension, the brass will simply yeild.

That is you can almost never get more than 0.003 in neck tension.

However, inserting a bullet into a dramtically oversized neck can lead to concentricity problems.

 

[wilecoyote]

Re: Question on neck tension

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: memilanuk</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">is .295 too much neck tension to be seating bullets into?</div></div>

Holy hell. That's way too tight!

Most .30 cal expanders (both expander plugs, balls or stems) I've ever measured mike out @ .306 or so. 2-3 thou neck tension on loaded rounds is *plenty* unless you plan on stabbing someone to death with 'em

More seriously... a little more might not be a bad thing for a gas gun or ammo you *know* is going to get handled roughly. Otherwise... I stand by the above.

I disagree somewhat with wilecoyote... a bushing die with the right sized bushing and either a polished or (preferably) floating carbide expander ball will not cause any ill effects. By 'right sized' I mean one sized so that the expander ball just *barely* kisses the inside of the neck on the way back out. That way you're not over-working the necks (which at .295 you most assuredly are), and not getting any 'drag' on the expander ball that could screw up the necks - or headspace.

Come to think of it... you'd have to be leaning on the press handle to seat a bullet into a hole that under-sized. I hate to ask... but are you sure you're measuring it right? What I mean is that some calipers have thicker blades for the ID measurement, without much bevel to them. I have a pair like that around here somewhere. It is *much* harder to get a good read on the inside of a case neck than with my 'better' calipers (Mitutuoyo Digimatic - spendy but worth it).

HTH,

Monte </div></div>Deadshot2 has has answered better than me

 

[Fuzzball]

Re: Question on neck tension

Do an experiment for yourself to see how much stretching a neck can take before exceeding it's plastic limit and deforming. Mike a loaded round at the neck, then pull the bullet and mike it again at the same place; there <span style="font-style: italic">might</span> be as much as 1 thou difference but probably less. Meaning any neck 'tension' amaller than the second measurement is meaningless for obtaining bullet gripping power.