i believe you could do some reduced velocity loading with H4227, or H335. should be interesting . finding a heavy bullet with geometry that feeds well might be an issue. up to 180 grs at subsonic, and a change of the recoil spring to one that has a few turns cut off would be the ticket, but what you would get is of questionable value. if you can go to gas checked 200 grs lead rn and about 1000 fps with reliable functioning, let us know. in that range of energy, hercules unique is a useful alternative.
phil sharpe published reduced loads as early as 1930, and was getting up to 1600 fps with unique and heavy bullets in 303, 30 russian, 30-06. the ak case is smaller, so loads would be reduced. pistol primers would conserve accuracy. unjacketed bullets work better at low velocity, but foul the gun quickly.
barrel twist rate is a factor in reduced velocity loading accuracy.