Barrel bore and bullet diameters are all over the place for the 7.62x39 mm (Russian) with the former measuring from 0.308" to 0.311" and the latter being 0.308", 0.310", 0.311" or 0.312".
7.62x39 Reloading Data - Guns and Ammo
Russian 7.32 x 39 in stock $ .41ea.
Why did Soviets love 7.62mm caliber so much that they even used it for pistols and submachine guns? - Quora
7.62 x 39 Russian Archives - 1967spud Reloading Supplies Ltd
AMMO] Golden Tiger - 1000 Rounds of Russian 7.62x39 FMJ BT 124GR - $190 + 22 S&H (.21/rd shipped) : r/gundeals
7.62×39mm, Military Wiki
Handloads: .223 Remington An Official Journal Of The NRA
5.45x39 VS 7.62x39 - Wideners Shooting, Hunting & Gun Blog
Howa Mini Action 7.62x39