Macho don't got jack sheet to do with any of it. Rob's not sticking arrows in the ground beyond the deer for who the hell knows why.....There are so many variables to consider, we could go on for years....Personally, I think it's the mechanicals, but that's my opinion. I wasn't there, I didn't see them, I don't know for sure. He's putting out more than enough KE, and more than enough momentum. Maybe the deer are moving one of their legs forward in time and in effect "pinching" the arrow to a stop.....I dunno....

I do know one other thing....If I drop my finished arrow weight down to 375 grains and it shoots 310 fps, or even 305 fps, I've got MORE than enough of both momentum and KE to do the job. So to the original question, why wouldn't I?