These are the patches I am currently using in most of my rifles and 20 bore smoothie. It is a bed or mattress ticking that measured .030" in the store, but after being washed and dried, mics .018" on a micrometer and .021" to .0215" with calipers, squeezing the tines together with my fingers, right over the cloth. The balls are pure lead and .562". Double thickness patch plus ball diameter adds up to about .006" larger than bore size.

This is the short video I took today during some further testing. Note that I usually choke up on the rod when loading. This helps prevent breaking the rod. Today, the 40th load in each tube, loaded as esily as the first two. At 110gr. of 2F GOEX, my barrels are shooting pretty much together on a vertical line, but still an inch to 1 1/2" apart. They are closer on that vertical line, than with 3 drams.
The Mounted Police Emergency Response Team was practising over on the pistol range so there is some background noise.