During WWII, Simo Hayha, a sniper for the Finnish Army used a Mosin Nagant M28 to kill 500 Russian soldiers in a 100 day period before he was wounded himself in the face (he was able to retrieve his rifle and kill the Russian sniper who shot him).
Simo preferred sniping from a sitting position, as he felt this gave him a very steady shooting platform. He used only iron sights as Scoped Sniping exposed too much of his head to enemy riflemen.
While small in stature, Simo obviously possessed tremendous eye to hand coordination. A remarkable man..........
I believe that his nerves must have been like ice - I personally cannot imagine the tension during that 100 day period.