Watched it. Oouch! Bet their wrists and tops of their hands talked to them next morning. See now they prevented rotation with two-handed grip.
Used to shooting 12g at times, one-handed. New to me guns I hold at arms length - never near my face when firing them at first. Bought a Stevens 311 SxS 12 at a GS. Think I wanted to check patterns close-up (small piece of plywood)on each barrel. Surprise. Had been modified to fire BOTH bbls if front trigger pulled first. Just a surprise, no pain, and no rotation as my forearm was on top of comb. No way I'd shoot that 45-70 derringer!! Pat