Could your alloy be too hot, burning off the tin as you cast? Ed
Ed,
I assume you meant to say boiling off the tin. Although pure tin melts at about 450 degrees F, the boiling temp is 4,716 degrees F, so there's no possibility it boils off.
Wayne
NRA & TSRA Lifetime member. NSSF member. Author & Publisher of the Browning 1885 BPCR book. See www.texas-mac.com