Simo Hayha, "The White Death" is considered to be the most effective sniper in Human History. He served in the Finnish Civil Guard during the Winter War with the Soviet Union in 1939-1940. Over the course of 100 days on the Kollaa Front, Hayha killed 705 Soviet Soldiers, including 542 with his bolt-action M28-30 Mosin Nagant carbine. He also refused to use a scope, making all of his kills with traditional iron sights.
Red Army snipers wearing the forest camouflage wrap-around that was issued in early 1943. Original caption refers simply to "Soviet snipers." Undated. Note the Moshin-Nagant rifles with the modified PEM scope.To this day, the M-N remains the most widely produced and longest serving sniper rifle in the world, and remained the Soviet Union's main sniper rifle until it was superseded in 1962 by the semi-automatic SVD Dragunov rifle.
The Mosin Nagant also saw service in Estonia after WW2 as a part of the Soviet Union. In the photo are Soviet (Estonian) soldiers in training. Notice the second rifle which has a bent bolt of some sort but does not appear to be a sniper rifle.