Surely it is that caliber.
This pistol (better known as TT in Serbia) uses 7.62x25mm ammunition, while the Zastava M70 automatic rifle (or the more popular Soviet AK47) uses 7.62x39mm ammunition.
I carried the M70 AB2 in the army, this M57 is my father-in-law's.
Ah ok, not a popular hand gun in the circles I've mixed in over the last 35 years, I guess due to there being far better options.