The Russian military adopted the AK-47 in 1947, chambering the 7.62×39 mm cartridge. An improved design rolled out in 1974—labeled the equally unimaginative “AK-74”—digests 5.45×39 mm, a completely different cartridge.
5.45×39 VS 7.62×39
5.45×39 VS 7.62×39
