I never tried any .429 cast bullets, but had pretty fair luck with hardcast .452 bullets using a Harvester .451/452 sabot. It seemed like the shape of the bullet base, if it matched up pretty well with the shape of the bottom of the sabot cup, was the key to good accuracy. The only lead bullets I used were very hard and didn't give any expansion. Best of the bunch was the 250 grain Keith style, made for the .45 Long Colt by Colorado Cast bullets out of Montrose Colorado. They shot about 2" to 3" at 100 yards out of my T/C Black Diamond.