I've been shooting .735 RBs from a Dixie Mould for years, mostly in a rifled barrel. They have given the best results of a good many slug trials. I started out with lab tested data from Gil Sengel, but as those components dried up, I switched to using any 1 3/8 oz load since that is what my balls weigh. When possible, I use Federal 12s3 wads w/ the petals cut to 1/4" since those are the only ones that seem tough enough. I do have some of Ballistic Products's Brushbuster wads on order since they look like they will work without the nuisance of trimming pedals.
Your Lyman RBs should work well when matched to bore or choke. A few thous larger than the choke should be fine, but I would not shoot RBs in anything tighter than the ball by .010 or more. I would seriously consider patching them to fit groove or bore diameter if they are undersized.
Crimps are critical. Any variation of crimp results in velocity changes and group sixe increase.
