The 50 Cal is not an anti-personal round, but it can be effective as such.
The best example I've seen was in SE Asia. Our A CO. was in danger of getting over run. On the high point inside the perimeter was a 50 cal gun crew. It was very successful in solving the problem but not by hitting people.
The rounds were hitting and busting up rocks, we found more damage done by chunks of rocks then the rounds themselves.
Its a good system, but not the end-all of weapon systems. It wouldn't replace the Med. MG, which would be better for personal. As a sniper system, its great on vehicles and harden targets, but can't compete with other systems in accuracy dept., against soft targets.
Personally I've gotten more use out of the 50 cal out of a 50 cal de-armor in EOD work then shooting.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071