I have spent some time trying to get PP to shoot in my C. Sharps rifle without lube, and have given up on the idea. I figured it works in the muzzle loader, why not in the cartridge gun? Well, the reason is the throat. You absolutely must not have gas blowing past that bullet at any point. And when you shoot a bore diameter bullet in a chamber designed for groove diameter bullets, things are real loose for a little while until that bullet is fully into the bore and can seal. Think about what happens at the moment of ignition. The case swells up to fill the chamber, the back end of the bullet is hanging out in the air unsupported, and nothing is keeping the gas from eating up the base of the bullet and tearing up the patch.
I proved this to myself by using the Sharps rifle as a muzzle loader. Chamber a primed case, load with enough powder to clear the throat (about 110grains in this case) use a card wad and a bullet. It shot great! But trying to get that bullet through the throat was giving me fits. So I started loading my fixed ammo with powder, card wad, two 1/8" lubricated felt wads, and a card wad. All of a sudden it started shooting! The felt wads must be providing a gas seal long enough to get the bullet into the bore completely. As an added bonus I stopped having to wipe between shots. I just use the blow tube for 5 breaths, and I am ready to fire again. I still haven't gotten it to give me what I would call gilt edge accuracy, but I can keep 'em in 4 inches at 200M pretty easily this way.
I still haven't tried a lube cookie. I suspect it would do the same thing, but that is next. I just need to come up with a good way to make lube sheets to try it. But the felt does work well. Oh, I tried Wonder Wads. They didn't work at all. But my homemade ones, cut at .460" and lubed with Gatofeo #1 lube work great.