The important factor with rifle loads, is the rifling engraving somewhat into the paper that wraps around the ball. This happened with mine, using a .682" ball in a .690" bore with .012" rifling. I used 2 wraps of about .003" or .0035" printing paper - 18 to 20 pound I think.
Note that I had to choke up on the rod to an INCH below my fist or use a short starter to get the ctg. started. Once started, I could easily run it down with one stroke. I could also fire up to 10 shots without any loss in accuracy or hard loading.
The 11th would start to get crunchy, and I felt it might effect accuracy, so I stopped ctg. shooting at the 10th, then fired a cleaning load of a mere 3 drams (82gr.) plinker, with a sopping spit-wet patch - then I could load and shoot another 10 ctgs. with perfect accuracy to 100 meters or more.
Now - I was also shooting 6 drams+ (165gr. 2FOEX) in the that rifle for a hunting load with both paper ctg.'s loaded with WW balls, or a cloth patched pure lead ball, same load, same poi. The velocity was 1,550fps, thus producing about the same pressure as 1,550fps loads do in any large bore from about .54 up, using 2F powder - in the 1980's.
With today's (2013) 2F GOEX powder, I get the same poi with only 140gr. as I previously got with 165gr. 2F GOEX. I have not chronographed the 140gr. 2F load - yet- I am hoping it gives me the same velocity or not, doesn't really matter, much, it shoots well right to 200yards and to the sights set up in 1986 when Taylor built the rifle. It kicks plenty hard enough with 140gr. that I see no need to shoot the25gr. extra.
I've thought about that, Dave - the shot in a paper ctg. Years ago, Ely had shot ctgs. for cylinder bored ML smoothbores. The ctg. included the shot and a wad under the shot. The shot was in a copper wire basket inside the paper. The paper was coloured to denote the intended range. The green ctg. was for shooting deer, wolves at close range or ducks out around 85 to 100yards - just a guess. There was a contest between an English hunter with a "nice little pistol", a 14 bore Westley Richards SXS and a long streak of famous bird killing hunter around St. Louis - can't remember his name. He had a long, 48"double barreled 12 bore. A 4" X 7" card was placed at 75 yards distance and the US hunter fired first, hitting it with 4 pellets - well satisfied. The 'prize' was the other fellow's gun. The English fellow chose a green paper ctg., loaded his gun fresh, and put 28 pellets on that little 4" x 7" card, easily winning the other man's gun. "Wal, thar fellow, you certainly have a fine shooting gun thar - here's o'l
?, you won her fair and skwar".
The 'story' of this contest noted that the English Gentleman declined the gun - saying "you keep her, you need her bore than I".
I have oft thought someone should, if wanting to develop tight shooting loads for their chokeless smoothie, should do some experimenting and get back to us here.
My 20 bore is choked and shoots right fine as it is.