I picked up a slightly used .50 cal DISC Extreme about two months ago.  I installed the Lehigh Gen II breech plug which you can get from Knight now.   A good combination for me was 100 grs BH209, 250 gr SST, Harvester .50/.45 smooth black sabot and bare Win 209 shotshell primers.  The 15th shot fired as well as the 1st one.