Rangeball,

71 ft lbs of KE....400 grain arrow traveling at 285 fps.

I would say that the entrance wound is somewhat larger for the naildriver when compared with a conventional two blade-cut on impact head simply because the "front surface area" is larger with the blades in a folded position. This coupled with the fact that the blades are forced open creates a slightly large hole in my opinion.

As for the exit wound...it was in a vertical slit shape though there was slightly more tissue torn out around the ferrule. I would say it is roughly equal to a traditional fixed blade head in this regard.