ORIGINAL: Doegirl75
ORIGINAL: ACPOSSETIM
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.
I sure hope you meant 4-5lbs of KE.

Sorry, I couldn't resist. After seeing personally the devastation they do on hogs, I would say that they are a solid choice.
No, I did mean 45#'s that is what your bow needs to have for K.E. for the heads to consistently open.