Used Wasp JakHammers for several years and have tried several other brands with different blade retention systems. I've never found one that 100% failure proof. Some open prematurely (paper test) and onmy last deer the double banded JakHammer (the only way to gurantee against premature opening I found) failed to open at all!
Luckily it was a heart shot, and I tagged the deer, but I'm back to fixed blades for now.
Not wanting to stir up an argument, but I've had a newmechanical headwith the clip/dimple system have one blade open when it went through the paper (from a 175# Exocet). New clip installed - same results. It may have been a one time occurance to get a bad one, but I'm not taking chances when I hunt, so that was the end of my testing with that brand. I have atwo strikes - you're out policywhen testinghunting heads.