ARs are like LEGO. You can do whatever the hell you want with them, and they'll be pretty danged accurate. No special tools required.
I'm a bigger fan of the .308 AR (AR-10, SR-25, etc.) platform than the AR-15.
I get 1/2 MOA out of my .308 AR off the bipod and I recently ran it through a 2-day class in dusty, grimy conditions without a hiccup. Without cleaning. You aren't going to do that with a FAL, AK, lever gun, or anything else short of a REALLY FRIKKIN' EXPENSIVE M1A or a decent bolt action.
Oh, and if you like .50 BMG, they make an AR upper for that too.
Zel Custom Mfg