Jim567 If you are getting tight groups at 100 yds--and I'll add my best handloads of 7.62 x 39 have been when using SST's--and then they fall completely apart at another 100 yds that seems awfully strange to me. The only logical reason I can think of is something is causing a radical destabilization of your projectiles. Pure conjecture, but whatever that is must have a threshold at the velocity/spin rate between 100 and 200 yds. I can't think of a condition where a weapon would shoot tight at 100 yds and for some mechanical error in the gun cause the projectile to "selectively" degrade it's trajectory at a particular range. I'd call Hornady--they are usually helpful when I call them, and see what they say. I'd try other ammo and chrono the results and see if the error was consistent. I guess it's possible if the bullet was not getting compressed to the bore properly (I think most AK type weapons on the US market are around .310 and I think that's what Hornady makes their SST's to) and it could be flying and/or spinning fast enough initially to overcome destabilization, though it seems odd it could be that different between 100 and 200 yards.