No Mutants Allowed

Sheer amount of momentum alone. It's the concussion damage.

What the woman said.

Ah so they be like a Mace or a flail for a heavy caliber gun like that? While smaller 5.56 Ap would be like a rapier with a tip made of tungsten getting through gaps in armor

The idea of "AP" could means something that does not easily deform and having hard enough body than the body armor that it made impacts with. Hopefully with enough kinetic energy left to do some damage once it made a hole through. Rapier is much weaker and has no place in this conversation. Because even if a sword like rapier penetrate, it doesn't have enough energy to "jellyfy" human tissue like bullet does.

Meanwhile, the reason why they went with a caliber like 5.56 is because the kinetic energy, it might have less momentum than heavier bullet due to the momentum formula (Mass1 x Velocity1 /Mass 2 x Velocity 2) but in term of kinetic energy, 5.56 has more to offer. Nevermind that the speed of 5.56 is such supersonic that it shatters the bullet when it impacts, resulting more tissue wounds.

I am afraid that you cannot simply use medieval weapons for analogy here.

sorry i have tendency to do that. Well that or they couldve adopted the 6.5x51mm. combining the best of .308 and 5.56 into one package like what the military is doing now