AR-15 .50 Action Express

Imagine a Desert Eagle, but as a rifle, with a longer range than a pistol.... Yeah this is what it is. It's up to 3 shot kill in the body, 2 if you're lucky, and 1 to 2 shots in the head ranged, but 1 shot in the head mid range to upclose (Hey it's a large handgun bullet, not a rifle bullet! :P)! A semi-automatic rifle that shoots as fast as a MSG90 or faster. What could help you more is a scope!