I have an M1A Scout Squad with not more than 500 rounds through it.

Two range trips ago, it blew a case rim, vented down the mag well, and blew the ammo out of the mag.

I inspected everything, didn't see any damage, but noted that the chamber was pretty dirty, so I cleaned and lubed per Benny6.

Took the gun out, put about 20 trouble free rounds through it, and called everything good.

Last week, third round blew the bottom off the mag again. Ammo in all cases here is that Malaysian surplus that was going around a couple of years ago for $0.40-$0.50 per round. Oddly enough, however I didn't start having trouble until I'd already shot 250 or 300 rounds of the stuff. (I know, they could have shipped me different lot numbers, and I have no way to check.)

Here are pictures of the chamber feed ramp, and the blown case. Please let me know your thoughts.

You need to find a good gunsmith to check headspace.
If it is still under warranty, send it back to SA with the cases.
It looks like a lock up issue,
but Malaysian may or may not be the issue.
I've burned alot of that and the only rifle that gave me fits was my SAR-48.
Wouldn't close on it, so it gets fed other stuff.

Looks like I need to make a house call...

I'll be there before July 1st. Give me a week or two to settle in and I'll have a look at it. First thing I'll do is check the headspace. We'll go from there.

I also recommend Lake City or American Eagle FMJ.

Tony.

I’d be a little suspect of that ammo, even though it may work fine 98% of the time.

Thanks to all. Looking forward to seeing you again, Tony.

I must admit that while I am inclined toward sourdough44's position on this, I do want to make sure the gun is set up properly.

Im going with bad ammo, too.

Ammo.