What's causing dents in brass

[remcraz]

This is Remington full sized brass. They are cracking at the bottom also. I am using the same reloading formula as I was and having no problem until now. What happened

 

[WeiserBucks]

Never mind the shoulder dents , that brass is done! You are either really over sizing your brass or have a serious headspace issue .

 

[remcraz]

When you say over sizing are you saying that I have used the brass too much and it is done.

 

[WeiserBucks]

That brass is about to separate just ahead of the belt . Read up on sizing brass and headspace for belted cartridges. It may just be worn out , but you could have a very real safety issue.

 

[Barrelnut]

IMO, the cracked cases at the web are due to repeatedly over sizing the brass and it finally wore thin and caused a case head separation.

The case head separation caused the big dimples at the shoulders because some of the pressure from the powder burn was lost thru the case head separation. The big dimples at the shoulder are often caused by not having enough pressure to seal the case at the neck and shoulder and it allows some of the gases to come back over the shoulder and makes the dimple.

You need to figure out the why of the case head separation....

 

[remcraz]

Thanks a bunch for the info. I just couldn't figure out what was going wrong. When I put the gun up it was shooting great and I sized the brass and it started doing this. I just kind of figured it was me doing something wrong

 

[remcraz]

I have shot this brass a lot so it's probably because of the oversizing

 

[WeiserBucks]

I would get to the bottom of it before loading any more. There's a lot of information out there on proper sizing of belted cartridges, read up on it and you'll be better off for the knowledge gained.

 

[remcraz]

Will do and thanks again for the help

 

[Beneviolence]

I'd guess gas is either redirecting into that area, likely linked to your near-separation, or you've got a dieseling effect (oil/grease in chamber igniting under pressure). Otherwise, I've seen similar effects from rough chambering in an AR-10; do you see the effect in an unfired but chambered cartridge?

As others have said, for safety sake you should address it before continuing.

 

[remcraz]

It's a new barrel with approximately 150 rounds fired before this happened. Never saw anything on the brass until I resized the brass and fired it today. I did all the prep work,full length sized,cleaned primer pockets and trimmed to length

 

[Barrelnut]

How many times was the brass resized and reloaded before the separation?

 

[remcraz]

I don't know exactly but just guessing I would have to say at least 5-6 times

 

[Gord0]

Are you saying that the dent is there after firing, or after sizing? If after firing I agree with others. I would also have your chamber and throat checked out. Make sure there hasn't been any flame cutting that's happened. Highly unlikely with only two rounds like that, but better safe than sorry.