7.62×38mm R
7.62×38mmR (also known as 7.62 mm Nagant and Cartridge, Type R) is a unique ammunition cartridge designed for use in the Russian Nagant M1895 revolver.
A small number of experimental submachine guns (See Tokarev 1927), designed by Fedor Tokarev, were also produced in a 7.62 mm Nagant chambering. None, however, were accepted into Soviet service.
Read more about 7.62×38mm R: Background, Handloading