During the early stages of World War II, the Mosin’s rifle was the main weapon among the Red Army soldiers. The popular name “3-line rifle” comes from its caliber, that is, the internal diameter of the barrel. It is equal to three lines. A line is an old measure of length containing 1/10th of an English inch or 2.54 millimeters — thus, three lines are equal to 7.62 millimeters.

In 1889, Sergei Ivanovich Mosin submitted a 3-line rifle to the competition. It was created based on his earlier single-shot rifle, many of its components, for example, the bolt carrier group and the receiver, being now part of the 3-line rifle. The three-line rifle of the 1891 model was approved by the Russian Imperial Army by decree of Emperor Alexander III. The rifle production began at the Tula, Izhevsk and Sestroretsk arms factories in 1892. Subsequently, the rifle model was modernized a number of times.

In 1932, the plants also launched the mass production of the 1891/31 sniper rifle. This model was distinguished by the improved quality of the bore, as well as by an optical sight and a bent down bolt handle. In total, over 100,000 produced sniper rifles were actively used during the First Soviet-Finnish War and the Great Patriotic War and have proved to be a reliable and effective weapon.

During 1941–1945, the Red Army and other military formations of the USSR received over 12,000,000 repeating rifles and carbines.