i cast my own, so i'm using a lyman 375 grain swc...seemed to be a good compromise between the light weights and the "thumpers" but the 400 grain slugs seem to be more popular and have more reloading data out there. oh, btw...they go all the way up to 700 grain slugs..
and..10 grains of unique with the 375 slug is a nice accurate light load ,a good load for "plinking" and targets...