My church security team were training Sat. and we all brought some rifles to break up the training. One of our guys had a kaboom in his ar. The magazine catch blew out the side and was hanging down due to gravity I’m assuming. I asked if it was a factory load or handload and he said all he he shoots is factory ammo. After I asked a few more questions he said that it’s happened on 3 other rifles. I was ruling out bad ammo on 3 different rifles. The one thing I noticed as I was standing behind him was that he was holding the rifle at the magwell. I don’t believe in coincidences so I decided if he’s holding the rifle at the same way is it a causal factor. My question is, would pressure on the bolt catch slow the bolt down enough to cause an out of battery fire. FYI it’s the first time I’ve ever seen it and he was lucky, a little powder burn on the heel of his hand, and the round in the mag was trashed. I kinda know the process of how an ar works but wasn’t sure about pressure on the bolt catch and mag because he was using it as a rest. I’ve built 5 ars (yeah I know, is that all), I’ve never had a problem out of mine. If I remember the rifle he was using was a Sig diamondback? I’m just not seeing the same problem happening with 4 rifles and factory ammo. Any thoughts?