Neck tension on bullet in .308

[GRIM]

Ok - so I usually use Winchester brass & either 175 or 190 SMK's. I use a .331 bushing in the Redding full length die. Seems to give me good neck tension. I also moly the inside of the neck of the brass.

So I was sizing some once fired Fed GMM .308 brass for my pet subsonic load and in this case I was using a .336 bushing due to the thicker brass. Somehow a piece of Winchester brass got mixed in with the Federal stuff and it went through the full length sizing die. I only realized this happened when I was seating bullets and when I placed the bullet on top of the winchester brass and the bullet pretty much fell into the case.

So what decides what the neck tension on the bullet is? Is it the bushing size or the diameter of the expander ball?? Since different size expander balls are not offered then I'm going with the neck bushing and that the expander ball only slips back through the neck and doesn't change what the bushing sized the brass to when it goes through the neck of the brass on the way out.

Anyone want to shed light on this?

 

[427Cobra]

Re: Neck tension on bullet in .308

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GRIM</div><div class="ubbcode-body">So what decides what the neck tension on the bullet is? Is it the bushing size or the diameter of the expander ball?? Since different size expander balls are not offered then I'm going with the neck bushing and that the expander ball only slips back through the neck and doesn't change what the bushing sized the brass to when it goes through the neck of the brass on the way out.

Anyone want to shed light on this? </div></div>


Bushings and\or expander balls resize the brass, bushings shrink the necks down to the bushing size selected, expander balls are usually .002 smaller that the bullet and you guessed it, open the neck back up, some people get rid of the expander when using bushing dies, and some who use bushing dies with the expander to just kiss the inside of the neck on the way out to remove dings in the lips of the brass.

 

[GRIM]

Re: Neck tension on bullet in .308

Yeah - I polish the expander balls on all my dies and I believe in using them since it keeps the inside of the neck concentric (I'm not benchrest shooting so the brass gets flung about like the rest of us after being ejected).

I guess if you normally use a .331 bushing then if you eliminate the expander ball and then try to seat a bullet you'll be too small in the mouth to get the bullet in so I'd imagine you'd have to use a slightly larger diameter bushing (if you are eliminating the expander ball).