Feel like a newbie asking about case stretch

[aquinas]

New DPMS SASS. 142 rounds through the gun. Loaded 50 new winchester cases with H4895 for ladder test. Loads ranged from 39.0 to 42.9 grains. First loading showed normal case stretch. Trimmed them back to 2.008. Book says 2.005 minimum and 2.015 max.

2nd firing produced virtually no case stretch. Out of 50 cases, most were right around 2.008. I had to trim 4 cases and those were just right at 2.015.

If this is normal, I've never experienced it. I always seem to have to trim my cases. Whatcha think?

 

[vman]

Re: Feel like a newbie asking about case stretch

if you FL die is set perfectly and you have trimmed your cases back it usually takes a while before they reach trim length again.

I dare say that an incorrectly setup sizing die will cause unnecessary work on brass and also increase the frequency of trims from shoulders constantly being pushed forward.

 

[InTheWeeds]

Re: Feel like a newbie asking about case stretch

It also depends on the quality of the brass.. I see a very negligible amount of stretch out of Lapua brass (from the factory, its already trimmed to 2.005") after 5-6 firings. BHA brass, I trim to 2.005" and usually only see about .004"-.008" stretch after 5 firings. Once the cases become work hardened from multiple firings, they wont stretch as much.

 

[vman]

Re: Feel like a newbie asking about case stretch

Yeh i forgot to mention that. I use Lapua brass so trimmings are few and far between

 

[427Cobra]

Re: Feel like a newbie asking about case stretch

Forget what the Books says, get a chamber length gauge from Sinclair and find out exactly what your trim length is.

 

[aquinas]

Re: Feel like a newbie asking about case stretch

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 427Cobra</div><div class="ubbcode-body">Forget what the Books says, get a chamber length gauge from Sinclair and find out exactly what your trim length is. </div></div>
What's the difference between a chamber length gauge and a hornady OAL gauge?

 

[Swan]

Re: Feel like a newbie asking about case stretch

It will also depend a lot on how high of a load you are running in the case. 43gr of Varget compared to 48gr Varget under the same bullet is going to have different effects on brass growth. Obviously.