Check out Night Owl Enterprises ( NOE) or Arsenal molds.
“Ranch Dog” designed cast bullets work well in Marlin lever guns- were designed with them in mind.
Shoot a lubed bullet .002-.003” over groove diameter ( .003” may be better for microgroove rifling. Slug your bore first. Arsenal molds with adjust cavity diameter for a design at NO COST. Them them what you are shooting for for final lubed diameter, and they will go for it. Then get the prober lube/size die. You may not need to size them at all, just pan lube them.
