Small hole blown in case - LMT MWS

[Yama Arashi]

This is some Federal Gold Match from 1991, shot out of a 16" MWS. 2 cases out of the 20 were like this.

What exactly is occurring here, and is it something to be concerned about with the rifle itself?

Pardon the lack of photo quality.

Thank you.

 

[RWSGunsmithing]

Re: Small hole blown in case - LMT MWS

Clean the gun and try a different brand of ammo. If it does it with another brand then there is a rifle issue, if it doesn't do it with another brand then the federal match ammo you have is the issue.

 

[[email protected]]

Re: Small hole blown in case - LMT MWS

Did you recently put in a new bolt? it might not be a tight fit and needs to be headspaced

 

[Yama Arashi]

Re: Small hole blown in case - LMT MWS

Any clue what the cause would be? Something with the chamber? Weak brass?

This was from the first time out with this particular MWS, and it was cleaned prior to shooting.

It didn't do it with any of the LC 02 surplus.

 

[Yama Arashi]

Re: Small hole blown in case - LMT MWS

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: x SNIPER x</div><div class="ubbcode-body">Did you recently put in a new bolt? it might not be a tight fit and needs to be headspaced </div></div>

Brand new rifle complete/direct from LMT.

The lower and barrel are marked 7.62, but LMT says the only thing different is the rollmark, and no specs were changed. (Compared to earlier models stamped 308)

 

[Ledzep]

Re: Small hole blown in case - LMT MWS

Weak/brittle brass. Maybe corrosion inside the case from powder breaking down.

Unless your chamber is oversized, I vote brass. Try some newer fgmm. If the newer stuff does the same thing it's probably the chamber. If not, 21 years took a quick toll on that ammo. I've had similar occurances with 1930's-1970's surplus ammo.

 

[straightshooter556]

Re: Small hole blown in case - LMT MWS

I too have seen this before and it was a brass issue not a problem with the rifle. Hard to really tell from the pics but it looks like there is some discoloration around the holes. You could cut the cases close to the holes to see what was happening inside.

 

[TGagnon]

Re: Small hole blown in case - LMT MWS

biggest issue I can see is flame cutting in your chamber. sort of like when a stinger sparks on the table while your welding and leaves a funny mark.

 

[DavidAR10]

Re: Small hole blown in case - LMT MWS

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TGagnon</div><div class="ubbcode-body">biggest issue I can see is flame cutting in your chamber. sort of like when a stinger sparks on the table while your welding and leaves a funny mark. </div></div>

We call that gas cutting. Means someone needs to get a new barrel, pronto.

Who/whom pays for it is another matter.

EDIT: Bet your bolt will close on a No-Go or even a da-da-damn 7.62 Field Gage {spelled properly}.

 

[Yama Arashi]

Re: Small hole blown in case - LMT MWS

Thank you to everyone for the replies.

Went through some recent manufacture A-MAX TAP today, as well as some more Federal GMM (still 90's stuff, but a different/newer box design, and obviously a different lot) and had no issues or case oddities whatsoever.

 

[Grump]

Re: Small hole blown in case - LMT MWS

Yup, brass issue.

Two shots venting that little won't flame cut a thing.

You can confirm that with close inspection of your other brass, all around the circle ahead of the extractor groove where those two pinhole failures happened. No bulges or marks = no harm, no foul.