I use lead bullets in my micro grooved 1894 357 Marlin made in 1984 as it happens. It’s conditioned for land use on open ticket and target for club use. I tumble lube .358 swc (rcbs mold) in lee alox and shoot them unsized with great results up to around 1600 fps with no evidence of leading. I use medium hard lead, range pickup which is around 12 on the bhs in line with Elmer Keith’s teachings.

I have found when I’ve slugged a few barrels that Rossi 38s tend to measure .356 to .357 where the Marlins are more .357 358 so a fat bullet works best. Lee mold bullets shoot like s..t in it. It could be they are too slim to properly grip the rifling.