I've got a fairly good handle on casting boolits for handguns and rifles; alloy, hardness, fit, methods, etc., but I just received a Lyman 525 Sabot Slug mold and am wondering about alloy/BHN. My first guess is relatively soft alloy, mebbe 9-10 (or my "mystery metal" alloy running 10-13 BHN depending on batch), but being a rookie shotshell caster, I dunno fer sure. Any thoughts?