Just a word or two about .41 Magnum bore & throat tolerances: IIRC, Brian Pearce noted in one of his excellent articles, that he'd found that any .41 Magnum & from a variety of manufacturers, in his experience, kept to the SAAMI tolerances: 0.410" bore with throats very close to that. He suggested that was the reason the caliber was so famous for out of the box, universal, accuracy....I agree.
My experience mirrors his with four Rugers (one 3-screw old model, and 3 NM's) as well as my Smith M-57 built in the early 70's. And when I was finally able to find a Marlin 1894S in .41, I found that, [contrary to Marlin's usual practice of overly large throats], it too exhibited tight tolerances: 0.410-0.411" bore & throat. Halleluiah!! Wish I could say the same for my .357, .30-30, .35 Remington & .44 Magnum's. All are accurate but all require lead alloy bullets that are 0.002-3" over normal groove dia. for the cartridge. These are all Micro-groove bbl's, to include the .41 Mag 1894S.
As a happy result of these tight tolerances in the .41 Mag 1894, I size no differently for rifle or handgun when casting my own: Lyman's 220 gr LSWC and the RCBS equivalent, both w/o gas checks and neither leads with moderately high velocities either. These are wheel weight alloy bullets, with a BHN of ~12, and I don't even bother to water quench them. They just work well enough as is.
It truly is, was, and will continue to be a well designed caliber with guns that took advantage of it's capabilities. Best Regards, Rod