No difference. The recoil springs are the same. Some, but not all, 5.56 AK's have slightly stronger springs. The milled receiver AK-47 and the stamped receiver RPK's, both 7.62 and 5.45, have a tube type recoil spring guide. The stamped receiver AKM and AK-74's have a loop type recoil spring guide.
Last edited by GIockGuy24; 06-09-2010 at 08:59..