I had a friend shoot a 120" deer with a spitfire late on opening day last year. It was so late he really didn' t know how well he hit the deer so we waited till morning to look for it. Good thing we did b/c the thing didn' t open at all. Luckily he hit it perfect and the deer expired 60 yrds. away. The blood trail was almost non existant all the way up to the deer. The mechanical head I have had the most success with is the Shockwave 100 gr. broadhead. The o-ring is located at the bottom of the blades so it actually helps it open. That would be my choice on the knid of broadhead to use.I have never lost any of the 7 deer that I have shot with one.