Neat old mold with the sprue cutter below the hinge. I've made quite a few bullet molds lathe bored and a few conical bullet cherry's but never have taken the time to make a ball cherry as one can get about any diameter of ball mold from Lee so cheaply it didn't make any sense to go to the trouble of making a ball cherry. Vaining a ball cherry with wave pattern flutes using a file is a real job although forming the round body with a hole die of hard steel after paring it down in a lathe would be pretty straight forward.
I'm quite sure these molds were never used much for volume work as by the time the mold gets hot enough to cast good balls the short handles are to hot to hold even with heavy gloved hands. I'd bet many a wrinkled ball was produced with these short handled iron molds.
I've never seen any with wood handles adapted to them either which would make them a great deal more user friendly.