Murf425 said:
If I get .53 balls, I would need .01 patches for a .54 rifle, right? Or would I need .005 patches?
In my opinion, neither of the patch choices would not give good accuracy in a .54 caliber gun.
Among the things that the patch does is to seal most of the gasses behind the ball when the powder ignites.
The .54 caliber Lyman GPR has a bore of .540 but it also has rifling grooves that are .010 deep.
That makes the groove diameter equal to .560.
A .530 diameter ball plus a .010 patch around it will make the outside diameter of the patch .530 + .010 patch on one side + .010 patch on the other side which adds up to .550.
A .550 patch/ball will not seal the .560 diameter rifling grooves.
A .530 diameter ball wrapped with a .015 patch has an effective diameter of .530 + .015 + .015 or .560.
While this does equal the size of the rifling grooves theoretically it would just "touch" the bottom of the rifling grooves. Not enough to begin to seal it.
A .530 diameter ball with a .018 thick pillow ticking patch has an effective diameter of .530 + .018 + .018 or .566.
This would have a .006 diametrical interference with the rifling grooves, or about .003 per side.
.003 is about the same thickness as one human hair so it isn't much but for most folks who shoot it it seems to be enough to give good accuracy without patch burn thru in the area of the rifling grooves.
I hope this makes sense.