The "classic" 148 gr. HBWC are swaged, not cast. They are soft enough to upset in the rifling at low, target level pressures, and are swaged by the larger bullet manufacturers; Speer, Hornady, Nosler, etc. You can get really close to HBWC accuracy with a good cast double end wadcutter, and I too believe these will be a hair more accurate than a shorter body SWC...
For my shooting, I ain't good enough to tell the difference in accuracy. My best group was 1 1/2" @ 50' with a mild load .44 Magnum and a cast 250 gr. SWC (I could usually get 2" most range sessions). A decent Bullseye shooter can shoot way better than that...