Denis, with all respect to the other contributors, I would not add tin to my beautiful pure lead. It will make an enormous difference in loading your rifle if you are using a tight combination, and I do. It doesn't make any difference if the balls are .003" under .440" as long as they are all the same, which should be the case. You will enjoy decent accuracy if you do your part, and if you miss, it won't be because the balls are .003" undersized. You should acquire a .445" mold as well, just to see if your rifle prefers the tighter combination that the larger ball would provide. The most important thing about shooting small groups on target, and hitting all the clangers on the trail walk, is CONSISTENCY. Your loads and the way you load them must be as consistent from shot to shot as you can manage.