Thankfully it was 22lr.

It happens. I call them KAPOPs!

I'm guessing "Massive" is a bit misleading. Wait till you have a real one. it happens.

What kind of rifle was it? And what do you think made it happen?

It's a 22lr AR-15 upper built by Compass Lake Engineering on a modified Army M261 kit. There are two issues that you need to watch when using this upper. First off the barrel is chambered with the Bentz chamber, so it's almost as tight as a high end match rifle. As the chamber gets dirty you start to get short chambering, and my upper can't go more than 200 rounds without before the chamber needs to be swabbed out.

The second issue is it's an AR conversion, and the normal timing of the BCG doesn't exist. It's possible to drop the hammer on a bolt that's not fully into battery. Combine both conditions and you have the OOB issue I had today.

Bottom line is serves me right because I was just thinking that I should probably stop and clean things up a bit, and pop went the weasel.

quote:

The second issue is it's an AR conversion, and the normal timing of the BCG doesn't exist. It's possible to drop the hammer on a bolt that's not fully into battery. Combine both conditions and you have the OOB issue I had today.

I had something similar happen with a 9mm blowback AR, and it was unpleasant. A little more forceful than your .22...all that was left was the case head. Then gun didn't break, and I didn't get injured, but I was glad I was wearing glasses because I took a lot of brass chunks to the face. There's a reason they designed the camming bolt system into the AR platform. I'm willing to take my chances with straight blowback .22s, but that blowback 9mm went away. It was replaced by a CMMG RDB system that uses a more traditional BCG/Bolt assembly, and although the lugs don't truly lock, at least it provides some timing and OOB protection.