The Mosin–Nagant is a five-shot, bolt-action, internal magazine–fed military rifle. Known officially as the 3-line rifle M1891, in Russia and the former Soviet Union as Mosin's rifle (Russian: винтовка Мосина, ISO 9: vintovka Mosina) and informally just mosinka (Russian: мосинка), it is primarily found chambered for its original 7.62×54mmR cartridge.

Developed from 1882 to 1891, it was used by the armed forces of the Russian Empire, the Soviet Union and various other states. It is one of the most mass-produced military bolt-action rifles in history, with over 37 million units produced since 1891. In spite of its age, it has been used in various conflicts around the world up to the present day.