Correction, I am that guy dumb enough to try it. Lol. Although headspace on my barrel was fixed to allow my bolt to properly lock and chamber a round.
before I had it fixed I knew that it not locking all the way wasn’t good... but not sure it would even shoot if I pulled the trigger, depends on where the bolt was in inside the carrier to allow the firing pin to travel far enough or not I guess.
after I had the barrel fixed, haven’t had any problems since.
theoretically, if it wasn’t locked all the way and did shoot, it wouldn’t be to catastrophic. Pretty sure it would just be like a cook off in an open bolt machine gun. Been there, done that, got a bit of case shrapnel in my cheek, a broken extractor, and a ringing in my ears.