The indictment should be on .223, not Marines. Less lethal calibre, more shots fired and more people with their panties in a wad over how many rounds it took to take the bad guys down.
I heard from a guy in the 3rd ID who picked up a British .303 at the beginning of the war. When he hit someone, they stayed down for good.
There is a significant portion of the domestic population who screams bloody blue murder every time it takes multiple wounds to bring down a perp wacked out on Angel Dust. "Excessive force".
You expect them to 'get it' dealing with doped up jihadis in an already adrenaline-rich CQB environment?
Maybe the .45 in a subgun would be a good item to have around--or bird/buckshot loads for the M203...