I don't have that barrel any more, OldMtnMan - however when Taylor gets the mould in for his 16 bore Lang rifle & casts some balls, we'll be heading out to shoot it.
At that time, we should be able to do a video of loading a .682" ball with a .034" patch in my .69 cal. rifle. I ran out of 30 thou. (12 ounce denim) patches, but a friend gave me some 14 ounce denim.
I have already showed, many times, loading a .0225" denim patch with a .445" ball in a .45 - loads slick as can be.
The video I wanted is now corrupted in Photobucket.
Here is my bro, Taylor, loading his .50, with a .495" ball and .020" denim patch. He uses a range rod, at the range. On the trail or at rendezvous, he uses nothing but the rifle's tapered hickory rod.
Only .0015" compression each groove due to the .016" deep rifling. Note with 100gr. of powder, this ball and patch combination fails- burns up due to blowby caused by the higher pressure and insufficient seal. At 85gr. of 2f, these patches show scorch marks, but still shoots well and does not need any wiping during a day's shooting.
Here is loading a .58 Kodiak with .008" rifling using a .562" ball and .0215" patches. This is quite a bit thinner than normally used by me - only .005" compression (oversize) in each groove, but it shoots well and never needs cleaning while shooting, right up to it's perfect regulation load (shoots parallel) of 110gr. 2F. My normal load in this rifle is 100gr. of 2f GOERX with the .0215" or .0225" patches. With this load, it shoots into the same group at 50 yards, ie: 1" c to c for 6 shots- 3 from each barrel. Due to shooting to the sights (1 set), the tubes are actually crossing, but the cross is only 1" at 100 yards, so still useable for hunting or target shooting. with 82gr. of 2f, the barrels shoot 3" apart in elevation and 2 1/2" crossing - useless for anything.
SRY - sounds condescending, was not meant to be.