Gunsmithing .005 case stretch with factory ammo?

[MTFalconer]

Ok someone verify this for me. I just got this back from my gunsmith friend and he is VERY good, I just wanted to verify this was within spec, I can't remember. Factory black box hornady 155 AMAX. Factory cases show variation of .001-.003 in length. Fired cases show stretch of .003 to .005. Keep in mind I didn't measure every case in the box for comparison to the fired cases it's just me being nit picky with a bunch of fired cases. Rifle grouped .780 this morning with this factory ammo,5 shots. I'm inclined to call it good but I wanted a second opinion.

 

[MTFalconer]

It calmed down a little with an average of .003 case stretch. I think I'll leave it alone.

 

[Fursniper]

Pretty normal, certainly nothing to worry about.

 

[Keith Johns]

Just enjoy it

 

[BurnOut]

I had a similar situation with a Savage that I had screwed together myself (read: I set the headspacing), and feedback from the Hide indicated that oftentimes, factory cases are noticeably short to ensure that they'll chamber. Sure enough, using the Hornady case length comparator set, I measured both the new cases and the GO gauge and found on average, the factory cases were .006-.007 short compared to the gauge.

 

[MTFalconer]

I used some of my hand loads in it and got an average of .001-.002, which is certainly acceptable. The .442 group above was shot with factory hornady black box Amax. Hand loads shot a .368 group with 155g Palma match.

 

[DAVETOOLEY]

Go to
WWW.SAAMI.org

And take a look around. It's all there. Chamber dimensions with +/- tolerances and cartridge dimensions +/-.