Almost like a slam fire but I can't imagine he's slamming the bolt forward hard enough to bounce the pin off the primer hard enough to fire it. The only other thing I can think is the firing pin is somehow stuck in the forward position and poking out of the bolt. When bolt moves forward and seats the round in the chamber it punches the primer. Crazy.
If that was the case you wouldn't be able to hear the hammer drop after he removes the safety and squeezes the trigger. It has to be a problem with the firing pin.the only other thing that i can think of is the sear is broken and the hammer is following the bolt with enough force to fire the round.
I don't think hes happy with his purchase....