Can't be. Everyone on the Internet knows AKs don't jam.
I'm with WA.. sounds like there's not enough oomph getting to the bolt carrier group. Try dissassembling the gas system and see if there's any gook in the gas port.
(i.e.. take the top cover off in back and take out the carrier group like you normally do when cleaning it, then move that little lever on the side of the rear sight block to about the 2-o-clock position. Then grab the top handguard and lift it up and away from the rifle. [obviously, this won't work with the rest of the guts in there, 'cause the piston on the carrier will be inside said tube]. Anyhow.. there should be a little hole in the top of the barrel. Make sure it's free and clear, and that the piston part of the carrier can slide freely inside the tube. )