T/C in my experience usually take the smaller of the two and Lymans for some reason like the larger of the two. I would get the .440 for the .45 caliber and .530 for the .54 caliber. I own six T/C .54 caliber traditional rifles. All of them shoot the .530 grain ball. In fact even my Lyman .54 caliber does. I have a .535 LEE mold for roundball that has only made about 200 ball through it in the last 20 years.I was never able to load them, so I use them for my wrist rocket. Excellent small game ammo.