Originally Posted by
Ned Christiansen
I agree (oob unlikely).
The only way I know of that an out of battery firing can happen, other than, say, a foreign object on the bolt face firing the primer, is if the bolt carrier bounces after the firing pin has done its duty-- only an issue on full auto. I'm not going to say it's impossible on a semi-auto gun-- one that's been diddled with as mentioned above or one that's just plain malfunctioning. Hammer follows bolt, fires the round as the bolt is bouncing, pressure has not dropped, carrier bounces enough to unlock bolt..... theoretically and mechanically not impossible I guess but that was pretty much addressed in the early '60's with the buffer as a bounce inhibitor.
Given a combo the wrong buffer, say one of the old Mom-and-Pop's Bufferama imitations with no stack of weights and rubber discs, an extra-strong buffer spring (or would it be extra light?), a heavy barrel for the carrier to bounce off of, a malfunctioning semi FCG where the hammer is following the bolt, soft primers that can react to the reduced hammer blow delivered under these conditions, and let's say we've dropped a round in the chamber and then dropped the bolt on it, so there's no stripping of a round from the mag to retard things just a tad........... I'm probably never gonna say an out of battery firing can't happen. But I have definitely not seen it all yet...... and these are only my opinions.
Going by what I see here it's not what happened. The sectioned barrel is chamfered/radiused as per normal and had 10K-plus rounds through it, no blowouts. To me it appears that Derek's case was in a chamber with about the same radius.
Feel free to use the images.