Thread: Split shoulders

Originally Posted by Magnetite

I did some measurements (probably not the ones needed).

There were two different weight projectiles which appeared to be: 139gr and 140gr Norma Vulkans. The 139gr was loaded with 45.5gr of an unknown extruded powder, and the 140gr with 45.0gr of what looks to be the same powder.

I measured the cases with a headspace gauge:

Undamaged fired case: 1.768"
Split cases: 1.766", 1.767" x2, 1.753"

Virgin cases: 1.761" x3
Resized cases: 1.740" x3, 1.776"

The loads are approximately 25 years old and were made for a military surplus Carl Gustaf. The shoulders split when fired in a Ruger 77 Mark II.

You do not measure cases to determine Head space , you use these https://www.brownells.com/gunsmith-t...uges/index.htm .
Military chambered rifles are generally use bigger dimensions than civilian rifles.
Milsurp cases are generally thicker .So you tend to use lower powder weights.
Here on pg42 you will find 6.5x55 case dimensions https://saami.wpengine.com/wp-conten...sting-Copy.pdf
First resized case is on the small size .
Basically your cases are of unknown age / stored for a long time in unknown conditions / Used in a Milsurp chamber / Used how many times ??. Candidates for the bin , they are worn out.