T/C in my experience have very uniform bore dimensions, I'd be amazed if your's was any different and required a smaller ball. Now, I'm going to throw some stuff out there that you will not like or may seem counter intuitive, I'm not trying to piss you off, I'm trying to help. First, I hope you are using black powder, not some pyrodex or modern formulation. I hope you are using 3F, most people use 2F and it works...but it burns dirty, has higher velocity deviations and is more sensitive to ramrod loading pressure. I hope that you are using fairly mild charges, I strongly recommend starting around 60 gr of 3F (you can stoke it up later if need be). Patch material...dig into your wife's sewing scraps and dig out a variety of thicknesses to test, do not charge the rifle, don't cut the material, at this point you are just fitting ball and patch combo to bbl dimensions and you will only shove the patched ball flush with the muzzle and use the excess material to retrieve the ball. Just use saliva for the fit test. Try to find a thickness of material that is just borderline thumb start but not so tight you need a short starter. Measure and record that thickness. Your patch material should be 100% cotton of the thickness you recorded. Now, patch lube, very controversial, but I will give you the most valuable roundball muzzleloading tip...never use anything but animal fats in the bore, nipple or pan area that is exposed to black powder flame. Ballistol is a mineral oil compound with a high ph factor. Rendered animal fat or Murphy's Oil soap in a water or alcohol emulsion(veg oil wood cleaner) or commercial grease like 1000+. Soluble cutting oils contain chlorine, I avoid them. Begin fire testing, read your fired patches, if you are still shredding patches, there is likely a rough spot in the bore. Last remark, TC generally is 1:48" so I would lean toward a little tighter patch/ball fit. (1:66 and 1:72 can be thumb started and seated in one smooth push, not much more than 10-15 pounds). It should never be so snug that it requires the ramrod to be 'bounced', which deforms the ball and ravels the patch.
