Here's another trick for all the paper patchers out there to think about: Cloth patching.
Some years back, I was thinking about paper patches and reading some muzzle loading literature that mentioned using paper patching in ML target rifles. My mind turned it around and asked "Well, if paper patches work in both kinds of rifles, cloth patches should too! So I went to my workshop.
I had a basement with a short rifle / pistol range at the time, and could play with stuff like this pretty easily. I got some thin cotton ticking from a fabric store, and loaded a 30-30 case with a light charge of bullseye. Then I proceeded as if a primed, sized 30-30 case was a rifle barrel: I laid a bit of ticking over the mouth of the case, added a single buckshot (I think a '00', might have been '0'), and pushed it flush with the mouth of the case, and cut off the excess patch with a scalpel. I repeated this several times to get enough to shoot a group.
Worked fine! All touching across the basement. I repeated with Unique, and got them hopping along fast enough that the buckshot turned into dust on the bullet trap, and still had good accuracy. I quit there, not wanting to contaminate my basement with lead any more than necessary.
Did the same thing with a 25-20 too. Even shot a couple of squirrels with it. The only 'trick' is to have a tight fit of ball and patch in the case mouth. I just used dry ticking, but some sort of lube on the patches would probably improve things.
Never had the chance to do any more with it, but have long wanted to try 'regular' cast bullets with 1) a short patch that just covered the bottom band as a cloth substitute for a gas check, and 2) fully wrapped like a paper patch: Wouldn't be nearly so delicate in handling, and should be a lot more protective, possibly enabling even higher velocities.
Hope this was interesting. I'd suggest you stick with cotton or linen cloth if you want to play with the notion. Synthetic fibers like nylon or polyester could melt and form some pretty stubborn deposits in the bore. Might not, but why take the chance?