Dan, don't go smaller with your bullets. If necessary, open the exit bores of your cylinder to 0.4300 - 0.4305". The correct way to do this is with a honing machine. Remember to keep your bullets the same size as the exit bores, or a bit larger.

I have not used Blue Dot in .44 Magnums but you might try some other powder before you ship your cylinder off for honing. I am very partial to #2400, though I will begrudgingly admit it is not the only powder for .44s. Give 18.0-19.0 grs. of #2400 a try (standard primers) and see if your leading situation changes. I'd think it would be worth the cost of a pound of powder.