and what do you think "packed" ammo means?
I suppose you might think it means "packed" into a magazine, LOL. But even if that were so, the 5.56 weighs about 1/2 of what 7.62 does, no matter how ya "pack" it.
whoops
The advantage over the M-14s was light weight, lighter weight of packed ammunition, far greater magazine capacities and no tell-tale PING! when the magazine was expended.