I have one very similar to SBHunter81's incident.

Summertime and I was in my backyard practicing for archery season with my new back tension release....one of the ones with a "safety".

I had by 70# draw weight hunting bow and was about halfway drawn back when the safety "popped off" on it's own and let the release fire. Arrow went into never never land and my balled up fist came back with at least 70 lbs of force and socked me square in the nose, knocking me flat on my back like someone just sucker punched me.

.....I sold that release shortly after the incident