Realmente ela não foi projetada para ser anti material.
É que eu vi num programa no History que no exército americano ela era usada principalmente contra carros e blindados, inclusive os soldados eram treinados para saber exatamente onde atirar contra um blindado para pará-lo.
Na wikipedia tem alguma coisa também:
The long effective range, over 1,500 metres (4,900 ft), along with high energy and availability of highly effective ammunition such as API and Raufoss Mk 211, allows for effective operations against targets like radar cabins, trucks, parked aircraft. and the like. The M82 can also be used to defeat human targets from standoff range or against targets behind cover. However, anti-personnel use is not a major application for the M82 (or any other .50 BMG rifle, for that matter). There is a widespread misconception that a number of treaties have banned use of the .50 BMG against human targets...
The United States Coast Guard Helicopter Interdiction Tactical Squadron uses a version of the Barrett M82 to disable the engines of go-fast boats carrying illegal drugs. Similarly, Barrett M82 rifles have attracted attention from law enforcement agencies; they have been adopted by the New York City Police Department. If it becomes necessary to immobilize a vehicle, a .50 BMG round in the engine block will shut it down quickly. If it is necessary to breach barriers, a .50 BMG round will penetrate most commercial brick walls and concrete blocks.
Notem que os soldados chegaram a ser desautorizados de usá-la contra alvos humanos, mas guerra é guerra...
santo.