Thread: Split shoulders

Originally Posted by Marty Henry

Ook please pass me that banana

Please read and understand Recovery Annealing https://www.ampannealing.com/about-brass-hardness/ .
Metallurgists discuss annealing as involving recovery, recrystallization and grain growth stages. In the recovery stage hardness remains relatively constant as some of the original properties of the brass recover,

Most likely your previous reloader has just reloaded the cases to their max. times and age has done the rest with storage being a factor .

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.

Greetings Magnetite,
I think I have spotted something in your measurements that may explain the neck splits. The fired case measures 1.768 inches compared to a new case at 1.761 inches giving about .007 inches of head space. This is generous but not unknown with factory chambers. Most of the full length (?) sized cases measure 1.740 inches. This gives .028 inches of headspace grossly excessive by any measure. This means that the base of the neck is worked excessively each time they are sized. I think that the handloader may have known there are problems and tried to partial size a case, the one measuring 1.776 inches. I doubt if this case will chamber. So to my eyes the principal problem is the dies which are grossly oversizing the cases. This is more common with continental military cases and my own 6.5 x 55 mm dies produce .008 inches of excess head space. I set the die off the shell holder to fix the problem. You have nailed the source of the marks on the case bodies as your storage boxes as suggested elsewhere.
As far as candle annealing case necks. There is a tendency by some to regard the latest kit as mandatory for good handloading and regard anyone who persists with older methods as a Neanderthal or worse. There is some science behind candle annealing provided the correct technique is used as written up by John Barsness in Handloader mag. I have been using it for about 3 years and have had excellent results. I will try to do a post on it in the future.
Regards Grandpamac.

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.

Originally Posted by Tankd

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.

Even if the cases are old etc chucking them wont cure the problem of the dies being incorrectly set or not matching the chamber. At this point we are not sure which it is.