Spaniel
Whatever manufacturer you get your bullets from make sure to get bullets with flat base design if you plan on loading 41 or 44 mag. to over about 900fps. I have not had great success trying to push bevel-base bullets faster than that.

I have used cast bullets from Valiant Cast Bullets, P. O. Box 696 , Bynum, AL. 36253 and been very pleased with them.

I bought mine at a local gun show avoiding any shipping charges, the cost for 500 was very reasonable. Midway might sell them , I know I've seen them advertised somewhere but postage might be prohibitive.