: The first is that the UNSC's MAC rounds are
: actually inefficient for killing warships. It's just like a regular bullet
: fired from a rifle; if it passes clean through the target, there was
: energy in the bullet that wasn't transferred to the target. A better
: bullet design would have it fragment, tumble, or otherwise disintegrate
: inside the target. A case like the Covenant warship coming after the
: Commonwealth after a MAC round punched clean through it would not happen.

I had thought about this too, though my figuring was that the Commonwealth's projectiles behaved like that because it was a warship from the very beginning of the war designed for crippling rebel ships for capture. So it was designed to be less than powerful because that war wasn't all out yet. Then we see examples of more effective MACs like the "shredder" kind mounted on the Autumn.