Last month a man was seriously injured after a cartridge was fired out-of-battery in his BOHICA Arms AR-15 .510 DTC rifle upper. The .510 DTC is one of those .50 BMG equivalents designed for countries where the BMG is banned. Despite the name, it is .50 cal.

One of the guys parents posted this at CalGuns forum …

Sunday a surgeon spent 2.5 hrs working to do hopefully the best work available to repair the damage. My Son, according to the surgeon had four broken bones and some ligament damage to his left hand, the one he was holding the gun with just in front of the chamber. If you notice the hole on the side of the I believe chamber is a vent, that’s where he received a good amount of schrapnel that broke his hand. The bolt lever was being pushed by his right hand/palm forward when the bullet discharged before the lever was locked into place. The result was a severe laceration to his palm but not as devastating as the damage to the left hand.

I met him with his mother and our daughter, his sister in recovery after his surgery he was quite depressed but glad no one else was hurt. His account of the event was the same Sunday night as the sedation wore off as on Monday evening when I visited him. No hammers, no channel locks, no tools no hang fire only hands.

We don’t know what exactly caused this unfortunate event to happen. I’ve been in contact with the mfg. on Monday and he seems quite concerned as I would be if I was producing an item like this. We will try to work together and determine what caused this event.

[ Many thanks to Marshall for the links. ]

UPDATE:

There is thread at ARFCOM about the incident (Thanks to JH1990 for the link). One posters said …

I was not at the range when this happened but I spoke with the range staff last week and they pretty much explained exactly how this happened. The guy was using new reloads that weren’t exactly fitting well into his chamber. Dude was slamming the bolt handle with his palm trying to get the cases to lock in. The guy was also slamming the bolt forward full force from the rearmost position back and forth trying to ram the cases into chamber in an attempt to squeeze the rounds in so the bolt could close. Finally, on one of the attempts of him doing this, the possibly stuck firing pin rams into the primer and explodes the round when he slams the bolt forward (zero lug engagement hence the KB) and shooter puts himself into a world of hurt.

The firing pin may have been stuck because the bolt handle was overtourqued (apparently it warns about this in the manual).

Another theory is a hang fire situation where the round detonated as it was being ejected.

Others have suggested that a faulty or modified trigger group bypassed the safety system (which prevents the hammer striking the firing pin before the bolt is fully closed) and the force of slamming the bolt closed caused the hammer to fall detonating the round before the lugs where engaged.

This photo is interesting …

It seems the bolt was forced all the way rearwards and then bounced back.