What did I say that is odd or confusing? It's as simple as different grain weights in the same caliber perform differently depending on the size of animal you are shooting. At least in my experience.
I shoot a couple hundred hogs and deer a year. A 150 grain partition out of a 270 Winchester performs markedly different on a pig if it is 200 pounds than it does if it is 75 pounds. The 150 partition doesn't kill the small pig as quickly as the 130 would. The 150 being a bigger, tougher bullet doesn't kill quite as violently on the smaller hog, though it still kills it.
Again, in my experience it is a matter of degree. Striking a balance between penetration and expansion instant drops. They will all kill, but as many as I shoot, I try to find the one bullet that will do instant incapacitation across the broadest spectrum of weights and sizes.
