That Accurate bullet is a good design:
That lube mix suggestion works in rifle length barrels.
Suggest you go with the iron mold blocks for durability.
Bullet ALLOY may matter. Don't be reluctant to harden until it is counter productive on accuracy. Wheel weight alloy is now all over the place so ratios involving it will produce erratic hardness.
Try 60:1, PURE lead to pure tin, then 40:1 and finally 30:1. Hard bullets also have less feeding friction for smoother action cycling.
Regards,
El Supremo/Kevin Tinny