Have cast .44 mag bullets for 20 years with linotype...none requireing gas checks. No leading problems. Just purchased a Lee 310 grain mold that requires a GC. Must I use a GC on this bullet even if my alloy does not lead my barrel? What about ballistics if I do not use a gas check..ie, tumbling, etc.
Also, this mold is .430 and my sizer is .429. Do I have to buy a new sizing die or can I size to .429 (I tried to size a few and it works with a little effort)?