I just picked up a Ruger American Ranch in 300 Blackout. I seem to remember seeing a bunch threads about people using faster pistol powders with cast boolits to create subsonic loads in non semiautomatic firearms but I can't seem to find them now.
I figure I may just play with 38spl load data for similar weight boolits to turn my Blackout into a bolt action 32-20 with robust, easy to find or form brass.
Does anyone have any thoughts, links, or loads they would like to share?