Thanks fellas!

by Hoot , Diversityville, Liberal-sota, Friday, November 14, 2014, 06:18 (3603 days ago) @ Hoot

I am not terribly bothered or mystified by the primer backing out. I've seen that on a number of cartridges, all of which were loaded lightly. And, as I have not done a chamber cast, there very likely could be headspace issues.

The bit that eludes me is what headspace issue or firing condition causes the case to shrink?

If, for any reason, the case is forced into the chamber far enough to set the shoulder back, then the neck gets longer, right? That brass has to go somewhere...

The only way I know to make a case shorter, other than mechanical trimming, is to neck it up or straighten the sides. Or, in other words, take brass away from the length and put it into the diameters.

As to the query if I am certain the brass was correct to begin with, no, I did no measuring. I can only say that all the remaining 8x57's in the house are about the correct dimensions. I could try and repeat the exercise and see if the results are the same...

I will note that a few different 8mm bullet and case combinations on hand chamber without trouble so the chamber is at least as big as the 8x57. Also, the fired case definitely sits deeper in the chamber than an unfired one...tough to accurately measure but by about the same 0.100".

I will do a chamber cast if, for no other reason, than to satisfy curiosity.

I very much appreciate the thoughts and suggestions.