Spitfire baby! They are a tough, solid, simple head that cuts a massive hole, leaves great blood trails, doesn't need o-rings or rubberbands to keep them closed, fly great, and only require about 45 #'s of K.E. to open.

here is a link of some slo mo test footage it shows a spitfire going through a cow femur and opening on a water balloon.

http://youtube.com/watch?v=Byvk_D35aOQ

Also they make a practice blade that replaces your hunting blades. I shoot them into my block with zero damage and the same point of impact.