Long Range Sniping
I think the whole idea of putting a .50 BMG cartridge upper on a AR-15 receiver, is not well thought out. Like I said previously, it will likely beat the receiver to death. If you are doing anti-personnell work, you are better served with a match grade heavy barreled .308 or .300 Winchester Magnum. I have seen DOJ snipers perform amazing shots with .308 Mcmillan (SP?) rifles. If going for anti-material shot's I would say a Barrett certainly could do the job, but I wouldn't want to pack a 35 POUND rifle, plus heavy ammunition, plus water, food, and all the other little things that come in handy living in a combat evironment. If you have a vehicle for your team, why not just throw the M2 in the HUMVEE, deploy, sandbag the legs do your camouflage thing, shoot the hell out of your target when it appears, and leave. A sandbagged M2 .50 caliber has an accurate range of TWO miles not one. If your target is stationary and your going to be helicopter deployed, the Barret makes sense.