I know this question has been asked before. Sorry for asking everyone to repeat themselves.
I cast Lyman 457125's for my '74 Pedersoli Sharps in 30 to 1 pure lead to tin. My rate is about 30 boolits per hour; a typical session is two hours of actual casting. When I weigh them, I get about a four grain spread. Aren't I supposed to be closer than that? I use a Lee ladle only pot, a Rowell #2 ladle, and the melt is kept at 750 degrees with a PID controller. The lead and tin all comes from Rotometals. The sprue turns frosty after about five seconds; I wait 25 seconds so as not to tear the base, then I tap the sprue cutter timidly with a leather mallet to cut the sprue. The boolits shoot fine, it just takes what seems like decades to cast a decent number of them that are the same weight. Of the sixty, I had five, five, and eight of the same weight to a tenth.
Recommendations?