Plastic Sig,
The 7.62x25 Tokarev round is a slight manufacturing variation of the 7.63x25 Mauser Broomhandle round (NOT the 7.63 Luger round, which is smaller and less powerful).
After WW I, the Germans, looking for trading partners, linked up with the Soviets, who were in the same boat. Germany sold the USSR something like 50,000 Broomhandles and ammo to go with it.
The BHs didn't go over all that well, but the round did. Through osmosis, the round developed a few very minor physical differences, but 7.62 Tok and 7.63 Mauser normally can be fired from the same guns with one VERY IMPORTANT EXCEPTION! (See below).
The Soviets kept the round when they developed the TT-30 (Tula Tokarev) pistol, from which the round gets its common name.
After that it was also chambered in a variety of Soviet submachine guns that saw heavy use in WW II and later with satellite states such as Korea (US GIs faced a lot of PPsH-41 subguns during Korea), Vietnam, etc.
The Soviets demanded ammo standardization within the Warsaw Pact, but the Czechs, wanting a more powerful handgun round, boosted the velocity/power of the 7.62 round considerably, and chambered the CZ-52 and some of their domestic subguns for this improved round.
It is this round that should NEVER be used in Broomhandle Mausers or really even Soviet TT semi-autos. It can cause the bolt to exit rearwards on the Broomhandle, and can batter the living hell out of the TTs.
The Chinese also used this round, and produced semi-auto TT-style pistols for it.
The Japanese, however, never used the 7.62 round. They had a rather anemic 8mm bottleneck round that was used in the Taisho 04 and Taisho 14 Nambu pistols, as well as the Type 94 (a true firearms abortion if ever there was one).
