Went out shooting today and had two cases that separated the neck from the shoulder, neck section came out on the first malfunction but the second stated in. These where once fired case full length sized and trimmed. I had shot a total of 40 or so rounds in a ruger 77, never had this happen before

Proves that stuffs happens.

What brand of brass?

A couple of years ago I had a box of Nosler 338 brass, normally excellent, that produced 8 vertical fissure cracks in the shoulder/neck on first time firing.

I bet you are over sizing them and setting the shoulder back. Maybe. Do not rely on the belt for anything; fit them to the chamber just like a rimless case. I am sure you already know that. Belted brass and chambers allow a huge headspace tolerance.

raamw,

I think dpcd hit the nail on the head. I've loaded literally thousands of 338 WM and never had a single issue. adjust your sizing die to just NOT touch the shoulder in the future and I bet you'll be fine.

Happy shooting!

Mark

quote:

I think dpcd hit the nail on the head. I've loaded literally thousands of 338 WM and never had a single issue. adjust your sizing die to just NOT touch the shoulder in the future and I bet you'll be fine

I would agree except for the fact this was their second firing. Never seen one stretched enough to separate that quick.
I'm more a not properly annealed guess. Hard brass failure.

I have 2 338's but I keep a couple of fired cases for each gun so I will go back to see if there is a difference, It happened with my M77 the BAR was fine

If any consideration was given to the fact the case neck does not touch anything in the chamber except the bullet I would believe someone would consider it impossible to separate the neck from the case when fired. Meaning there is no way sizing, bumping and off setting the length of the chamber with the length of the case could cause ‘case neck separation’.

And then there is a very remote possibility the bullet welded to the case neck. After that there is that complicated chain of events that take place when the trigger is pulled and the firing pin crushed the primer.

I was given 80 cases of 7MM Remington Mag by another reloader. I asked him if the cases belong to him and he said no. I then suggested we go visit the then shooter/reloader that gave them to him. That was not going to happen because he died and he did not know what happen t the rifle. Anyhow, the necks were caked with carbon the thickness of the carbon could be measured.

If I was loosing case neck I would clean the chamber and remove carbon build up, and then I would change powder, or get bigger bullets or something that could cause the case to expand and seal the chamber before the hot high pressure gas blew back between the case and chamber. Because if I don’t there is a chance I could start loosing case neck.

F. Guffey

quote:

Meaning there is no way sizing, bumping and off setting the length of the chamber with the length of the case could cause ‘case neck separat

Got to disagree with that; if your shoulder is not supported, it has to blow forward with each shot. Combine a bit of hard or brittle brass, and yes, the neck will come off. It is rare because most brass is very ductile there, but it can happen, as ramrod said it would. The floating shoulder and brittle brass cause it.

Every case I have seen crack at the base of the neck circumferential, has been caused by brittle brass or age hardening. This is generally in brass that has been sitting loaded for some time.
I had it happen to me regularly with 25-06 Winchester brass, the only fix was to anneal it every other firing. Even 3 firings, and the brass was brittle again, it must have been the alloy content. No other 25-06 brass I have has done it.

Cheers.

DPCD is absolutely correct, however once fired brass should not come apart that fast even with setting the shoulder back, normally you will get two or three loadings before that happens, unless you have a sloppy chamber..

I could guess and by gosh what happened in your case, but to what avail?...

Blacken the neck and shoulder of your case with a wooden match flame, so you can see how far down the neck its sizing your case, forget the belt, then try the case in your chamber resizing more and more, until you get a ever so slightly snug fit, then with hunting ammo set it back just a bare tad more..your brass should last considerably longer..