I have an unmarked mold that came with a rifle I acquired, the only marking is S and a B Cast a few bullets and they measured .459 bottom band .457 grease bands OAL 1.435 weight 535 grain looks a lot like a postell bullet,the rifle is a Parker Hale .451 I am guessing who ever had it sized the bullets, mold has no other markings perhaps a custom mold any input.
Thanks