I'm using a new "Mountain Molds" double cavity, aluminum mold. I'm trying to cast .511", 535gr, Lyman #2 alloy. The sprue isn't cutting off cleanly and my bullet weights are varying from 530-536 grains. I've tried adjusting the tension on the sprue cutter without too much pressure, varying the hardening time after the pour, paying attention to temperature differences of the molten alloy (between 650-800). After the initial warm up, the bullets fill the cavities well. The dramatic weight varyances concern me. I'll be installing Gator long gas checks but without trimming the "cut off nipple" on the bullet base, the gas checks will want to and do, rock on the bullet base. Help please...