I had a 15/16" TC barrel bored from .50 to .54 as well as a C weight Rice barrel bored from .50 to .54. It depends on who made the barrel and what size it is.
I checked the Rice Barrel page, 13/16" to .45, 7/8" to 50, 15/16" to 54, B weight Barrel to .50, C weight to .54, D weight to 58.