Even after rechambering older Vx.52 rifles to use the 7.62x39mm cartridge, the Czech’s replaced them with the Vz.58. It looks like an AK but aside from caliber that’s where the similarities end. The 58 uses a short-stroke piston, whereas the AK uses a long-stroke piston. The 58 can also be loaded via stripper clips like an SKS. On a magazine related note, although it looks like a standard AK mag, the 58 uses it’s own proprietary mags, the two rifles can’t interchange magazines in spite the similar appearance.