I received my 3 Roundball molds in the mail yesterday and finally found some time this afternoon to give one of them a try. I ordered a .590 RB mold for my .62 fowler and since I didn't have any balls left for that gun I thought I'd try it out first. I did a thorough cleaning with Dawn detergent, hot water and a toothbrush.
My Lee 4-20 pot was filled with pure lead and set at about 6 1/2 on the dial. I pre-heated the mold on a hot plate and started casting. I found that the mold preferred to run hot, otherwise I had minor wrinkles. Once the mold got up to temperature casting and dropping them was a breeze.
The square sprue hole is novel but does seem to cut somewhat easier than the traditional round sprue. I don't see any reason that a square sprue should affect accuracy compared to a round sprue.
I measured the newly cast roundballs and they came in at .591 - .592, perfectly acceptable for my use and well within the stated tolerances mentioned on the Group Buy.
Here's some pics of the mold and cast balls:
Needless to say, I am very happy with the results of this Group Buy! Thanks for running them for us JT.