My first post here.  Changing the hardness of the alloy changes the as cast diameter.  We all use WW plus tin now, but Elmer used I think, 1 part tin to 16 parts lead in the .44 magnum.  WW has arsenic and antimony in it, which is actually good.  That 1 to 16 mix is not a real hard bullets by today's standards.  Alliant 2400 has been changed in the last few years.  22 grains with a 240 grain cast bullets is too hot according to them.  The reason it was changed was because of possible use as a bomb making material.  If your mold is not big enough some manufactories will resize it for you.  You can also polish it out yourself.  Check out the The Cast Bullet Association site, Castpics, and Castboolits for information.