The Mosi-Nagant rifle, also known as the Vintovka Mosina, was developed by combining two competing designs from a USSR army captain Mosin and a Belgian designer Nagant. The final design was an amalgamation of both designs. The original Mosin-Nagant was originally developed in 1891 and, between then and 1944 the Mosin-Nagant went through several re-designs, and the variety that was used both for the infantry and as the sniper rifle was known as the M1891/30, and was producted in 1930. Like the Karabiner 98K, the Mosin-Nagant is an internal-Magazine clip-fed rifle. In the game's manual it's called M1891/30, but in the in-game variant is the M38.
Mosin-Nagant M38 on Wikipedia