Thread: Split shoulders

Long story short. I got some handloads (I didn’t fire any and they have been disassembled). After inspecting the fired cases I noticed the shoulders and necks where severely split. What is the likely cause? I did find corrosion inside the unfired rounds and the fired rounds weren’t fired in the rifle intended for the load.

The brass is corroded and/or brittle with age. Some old brass is perfectly usable after annealing to deal with the brittleness of age. Some old brass is corroded due to bad storage so much so that it is unsafe to fire and if fired, splits at the shoulder and the neck or in the body of the case.

Greetings Magnetite,
I had some Federal cases crack just like that. The cases were range pick up, I think once fired. About half the cases cracked just like that first time which is unusual as my experience cracks usually develop in the middle of the neck. The survivors were neck annealed with a candle and have and have given no more trouble neck sized in the same chamber. The cases were in one spot on the range and I assume they came from the same rifle. I wondered if they had been fired in a military semi auto which often have different chambers but really don't know. There was no sign of corrosion.
Regards Grandpamac.

Normal in my 270 wsm after a few reloads

I think that combined with the points made by others that there is also something going on with the way the cases have been sized. They haven't got a nice crisp clean shoulder like they should. Sort of looks like they have been neck sized leaving a donut then at a later date had a real 'crunch too far' full length size

Thanks for all the help. MOA Hunter I think you might be on to something. Here’s a picture of the unfired cases. I think the left are virgin cases and the right are once fired.

The ones on the right are once fired and then full length sized / prepped cases ? is that correct. Which if loaded as they are then turn into the side ventilated type first shown ? What is the difference in shoulder diameter between left and right ?

Can someone who knows more about this than me step in here please as I am guessing / hunching

To have any hope of a Diagnosis ' more information is needed . Rifle / age /actual load . for a case to fail what happens is that it is forced to work beyond its acceptable limit . This can be a brass or even rifle problem , but the answer will be found by measuring the rifle ( not as easy as it sounds ) or by measuring the brass pre and post firing .
Giving the Rifle a real good clean ( chamber area ) is a good start and then measure cases including thickness of the brass . I had a split case problem with a FR8 , I solved it by using Milsurp brass because it is thicker . And PLEASE do not buy into the ridiculous practice of annealing things with candles ,that is the preserve of monkeys .

Originally Posted by Magnetite

Thanks for all the help. MOA Hunter I think you might be on to something. Here’s a picture of the unfired cases. I think the left are virgin cases and the right are once fired.

The ones on the right look like they were sized deeply and with unannealed brass they do a lot of effort on firing to the chamber.

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.

Originally Posted by Tankd

To have any hope of a Diagnosis ' more information is needed . Rifle / age /actual load . And PLEASE do not buy into the ridiculous practice of annealing things with candles ,that is the preserve of monkeys .

Ook please pass me that banana

There's more than one issue here.. hard to tell if those marks in the sidewalls are the start of case head separation or marks from the chamber or dies.. the damage on the rims look like extractor gouging from sticky cases or from the shell holder from stuck cases due to lack of propper lube in the dies.
Check the inside of case where that ring is for a groove..
Hard brittle cases or over work hardend/sized will case all this especially if they are sized outside of a few thou head space tolerance

I had that happen to nearly 50 out of a bandolier of 50 wartime mk7 .303 headstamped GB or something, someone at the range told me that was a UK manufacturer. The particular SMLE implicated was my one with the most generous/excess (a matter of viewpoint) shoulder space. Anyway those two planets, "Brittle" and "Stretchy" aligned for split shoulders and necks to occur.
That said, the bullets all flew nicely downrange as intended apart from frequent clickbangs, and the brass was Berdan primed anyway, so as long as no case separations it was just another day at the range... (-:

Would the trick be to fire a couple of new factory rounds and post a picture here of the cases for comparison ?

Originally Posted by Wingman

There's more than one issue here.. hard to tell if those marks in the sidewalls are the start of case head separation or marks from the chamber or dies.. the damage on the rims look like extractor gouging from sticky cases or from the shell holder from stuck cases due to lack of propper lube in the dies.
Check the inside of case where that ring is for a groove..
Hard brittle cases or over work hardend/sized will case all this especially if they are sized outside of a few thou head space tolerance

I checked for case head separation and couldn't find any. The marks in the middle line up with the container they were stored in. As for the marks on the rims, they are from a shell holder in an inertia puller.

So far I'm guessing it's a combination of the shoulder being pushed back too far and the cases becoming brittle with age.

Originally Posted by Moa Hunter

Would the trick be to fire a couple of new factory rounds and post a picture here of the cases for comparison ?

I'll see if I can find some factory cases from the rifle.