ORIGINAL: cayugad
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.
I have both a .50 & .54cal T/C barrel and both of them shoot best with a .005" undersized ball. I think this just points out that you really need to try both the .005" & .010" undersized balls and see what works best in your barrels. I do know that because of the shallow rifling depth of the rifling in the T/C barrels, you will get the best accuracy using the tightest ball and patch combination that you canload but you probably don't want to have to hammer the ball and patch down the barrel each time.