As I am fairly new at casting, I have a couple of questions. In casting for a 45-70 with a rcbs 45-405 mold using just wheel weights and pushing them with imr 3031 how fast can they be pushed without needing gas checks or adding a bit of tin to them? Also my Hornady gas checks won't crimp onto the base of the boolits when run through a sizing die that measures as small as .457. I am changing to a sizing die that measures .459 so how do you make the gas checks stay on the boolit.
Also, should I use tin or antimony for hardening or does it matter?