I am not sure you are looking for the right thing. Bullets that shed weight are not more efficient than those that hold together. A bullet that disintigrated would probably penetrate less as well.
I keep getting very good one shot stops with my handload of 170 grain Speer FP, and 35 grains of 4320. The expansion is moderate, but the bullet almost always stays in the animal, and they drop dead just like clockwork. Who could ask for anything more?
