If it was a Ma Deuce he was probably lobbing bursts of rounds in the general direction. This was not precision long range classic sniper shot...not with a machine gun.
I seem to remember Hathcock cycling a single round from an M2. He was the antithesis of a spray and pray guy.
Incorrect. The M2 trigger has a latch below it. IIRC, if you rotate the sleeve, it secures the latch and permits automatic fire. Rotate the sleeve to the right, the latch is released and the weapon fires semi-automatically.
The barrel rifling is more than adequate for precision fire in semi-auto mode. All you need is a good sight and understanding of the impact of weather and terrain upon your round as it travels to the target.