I think bullet construction and or design is the main issue here....Partitions are designed to penetrate deep and expand on medium to large game and not constructed like a lighter jacket or exploding varmint round ! Speaking of the Fusion ammo , I got my first two deer with my new .243 caliber rifle with it and they went down as fast as the deer I've taken with a .270 , 30-06 , 30-30, 44 magnum , or my favorite 45-70 lever gun !