RON L here = SERESURPLUS
OK, I get the general "Gyst" of the problem, both mags tested, feeding not different, cleaning, no effect, is this with different ammo? You might want to try fresh ammo from a different box and or Lot and try different bullet types, I.E. FJM, H.P. and so forth? When the two different mags lock in, does the lock up seem Normal? That in, the mag rocks back and solidly locks in place? Any Movement side to side about normal? All this matters as you might still want to try a different mag, what might have gone wrong might have buggered up the two mags? Not seen that, but it's been known to happen in other self-loading rifles! I'm sure I'm covering gone over ground, but does thier seem to be any difference in appearence inthe magazine well? That is, is the area smooth and clean? Does it show any Burs or more importantly Gouges? All these are signs that something affected the magzine lock up area and feed path? What sort of Jam do you get? Does it batter the rounds into the top of the reciever body at the top, Botom or side? Seen a damaged feed area once in an M-1 carbine do that, never in an SKS or AK, but never say never? With all that tested if it's still doing it, might be time to take to a Good Gunsmith? Lord knows we don't have any here, but hopefully you will find out whats wrong yourself and not need one?
Please keep us updated and what you have tried and what you have found? This one seems like a hard one? Time will tell? Get back to us after you've tried a few more thing, OK? We care about you and the problem and hopefully we can sudguest some cure for the AK ills?