What caused my case to do this? (Help)

[snider6464]

I have a 30-378 Weatherby that i handload for, everything has been fine except these two cases. All the rest of the rounds that i have fired have been fine all 180 of them. These seem to have folded in just behind the shoulder after i fired them, again this was after i ejected the round i discovered the defect, was fine when i loaded the round. these were around 20 rounds apart as well. any thoughts? Thanks

 

[MALLARD]

Re: What caused my case to do this? (Help)

some piece of crap was right there when you sized or fired it?

 

[snider6464]

Re: What caused my case to do this? (Help)

thats was i originally thought when the first one happened, but when it happened again a month later, thats when i kind of ruled that out. It happened when the case was fired. I was leaning toward low powder charge...? even though berger says for the 210 grain you need to be between 94.5 - 99.6 and i load at 97.0 so not to low by their standards...

 

[Radar360]

Re: What caused my case to do this? (Help)

tag

 

[HPLLC]

Re: What caused my case to do this? (Help)

From what your describing (putting a good case into the chamber, firing, and pulling that out)-

It seems to suggest some pressure is getting between the chamber and case and pushing it in.

I've seen very thin spacers in sound suppressors that have failed in that way at 1400-1600F, the brass casing is really pretty similar to that, only typical theory is that pressure is supposed to hold it against the walls of the chamber through the firing cycle.

I don't know what specific conditions create this kind of issue as it pertains to brass, or how to prevent it.

It just doesn't look like a mechanical object caused those features.

 

[snider6464]

Re: What caused my case to do this? (Help)

So there could be a very slight gap (or headspace issue) that is causing pressure to moving down the side (outside of the) case in that one spot making an indentation?

I think that is a large possibility.

my question is why hasn't it occurred more? could neck sizing compared to full length sizing help cause this? because I have switched back and forth from just neck sizing to FL sizing...

The bolt was not extra hard to move into position

 

[Fuzzball]

Re: What caused my case to do this? (Help)

Your loads are too light to reliably force the case neck to expand and seal the chamber. Blow-by is pushing the cases in but it's harmless, shoot 'em again and they will blow back out.

 

[Tripwire]

Re: What caused my case to do this? (Help)

Note the soot all the way down into the radius of the shoulder....

It's a Weatherby.....pump up the volume.

 

[LAmenace87]

Re: What caused my case to do this? (Help)

check the chamber and casings for buildup of lube/ moisture. the temp of the shot could be causing the lube/moisture to evaporate and denting the casing. sounds like bs but have seen it before on my 25-06 when deer hunting in the rain.

 

[arnie19]

Re: What caused my case to do this? (Help)

Anneal the neck and shoulder area .Arnie

 

[Bear_308]

Re: What caused my case to do this? (Help)

The only time I've ever seen this issue was with excessive case lube during the reloading process.

Are you 100% sure these cases couldn't have slipped through the reloading process unnoticed?

An inward bulge like that seems tough considering the powder explosion/expansion should fire-form the case to fit the chamber.

Just my $.02 ... doesn't hurt to go back to the beginning and confirm the basics before trying to explain it from the final step in the process.

Bear