Well, the answer to thisis simple, but not necessarily the least expensive.I use the biggest ball that I can get started into the bore of my rifles with the patches I am using, without deforing the ball when loading. TUse of the largest ballis particularly necessary for utmost accuracy when target shooting, but is not as significant when hunting. When hunting, a looser patch-ball combination will let you reload faster, even though not quite as accurate.

There are three measurements that are important - bore size of your rifles, diameter of the ball, and thickness of the patch. The combined diameter of the ball and the thickness of the patch should allow your barrel to have a very firm grip on the ball, and fill the bore to the bottom of the grooves. There should be an imprint of the patch material on the lead if the ball all the way around, not just on the portion of the ball where the lands force the patch into the lead of the ball more deeply than in the groove portion.

I would recommend that for starters, you try a .445" ball for the .45, and a .530" ball for the .54. Get some precut, lubed .010", .015", and some .020"thick patches. Either the .010" or .015" patches should work well in the .54 with .530 balls, and the .010" patches should work with.445 balls in the .45. However, if these patch/ball combinations should prove too loose in either rifle, you can go to .020" patches in the .54 and either .015" or .020 patches in the .45.

Later, if these balls don't work well, you could try the .440" balls in the .45, and the .535 balls in the .54. But I'd bet the .445's and the .530's will both be OK with the right thickness of patch.