Even though it doesn't say Lyman on it I'm thinking it was made by them maybe for TC in the day. Could not find any reference to that mould number anywhere on the web. Got this from my fathers estate when he passed away though don't know why he had it because he never owned a 50 so don't know any other history on it. I have a couple 50's but only shoot round balls. It casts fine as you can see from the pictures. I didn't let the mould get quite hot enough so they aren't perfect but you get the idea. In pure lead it measures .54 at top and bottom 2 bands are .52. $50 + shipping.