I've been working on my own here trying to get some cast boolit loads for my Marlin .357 magnum. I started with some 158 gr gas checks and Carnauba red lube sized .358. Couldn't get very good accuracy. Someone on this forum suggested sizing to .360" for the microgroove rifling. I don't have a sizer in .360 so I cast up some unsized and powder coated them. The green boolits are PC'd using Smoke's John Deere Green powder. Cast from straight COWW.
Took them out to the pit and shot some targets at 50 yds with receiver sight and brass bead. Got several inch and a half groups. Now I'm happy. My marlin is shooting those boolits at least as well as I can.
The COWW produced some nice looking boolits.
Now I'm trying some softer boolits from the same mould. 49% COWW, 49% Pb, and 2% Sn. Powder coated with Smoke's gloss black to tell the boolits apart. Still accurate. No leading.
Edit: Am having trouble attaching images. Is there a place I can get straightened out?