you left out the details man. sp for the most part expand (ive seen some barely expand) loosing alot of the energy. some expand to well and are found in lil pieces throught the animal, much like a hp. but sp are meant for stoppin power and to creat big enough wound to mame or a quick death.You are correct about sp bullets, but the difference like some have stated is that the fmj will not expand, which when a bullet expands it also displaces most of its energy into the animal that is hit. Even though the bullet passes through you will have a quicker kill than with fmj.