Quote Originally Posted by Husar View Post
Ok, so if the two rounds reach their target with the same kinetic energy and have the same shape and materials (+ density), the 5.56 is faster and the 7.62 has more mass, but overall kinetic energy is the same as I said, would there be a difference in penetrating power? Would the mass of the 7.62 help it penetrate because it simply is harder to stop and would the smaller size of the 5.56 help it get through as it has to "cut a smaller hole" to get through whatever is in it's way?

I'm wondering about this because if caliber and weight are so important, why do tank gun designers increase the velocity of their penetrators instead of weight and caliber? I would think a very, very fast small bullet should cut through armour quite well, after all it take less energy to shove a needle into your skin than it takes to get a pencil there., even if it's a very sharpened pencil, or am I wrong? (not feeling like testing that last thought right now )
At that point I think the 7.62 would still have the advantage as it would retain its mass better than the smaller 5.56 which would break up a lot faster.