Good to hear you've had luck with them, I think that any head can be as deadly as any other head its just more about placement and there's so many variables to them, I've seen deer run with no heart for hundreds of yards, and I've seen them hit in the liver and go 25 yards and pile up, from what I can gather it almost seems like some deer just have no will to live after they've been wounded, granted some aren't like this, even the vast majority aren't but I can remember my friend shooting a buck that was all beat down and he hit it in the brisket with a rifle, that deer laid there and did nothing and he just jacked another shell in and put the hammer down on it, but the deer just showed no desire to live at least that was my take on it. I also think that if you stop the deer by making that mmmp noise it puts a shot of adrenaline into them and that makes them go on that adrenaline rush, kinda like if your walking through the woods and you don't see someone and they yell Boo! I have weird points of view but I just sorta think that any head can kill a deer really if placed correctly. Not doubting your success with the new heads or doubting your story at all just throwing my experience and opinion out there.

Ryan.