I used to have a Bullberry Contender barrel chambered for 25-20. I fought with that thing for a long time trying to get it to be accurate, and finally put it away. Same thing with a 256 win mag one. Then I got older and more experienced, and learned more about how to get guns to shoot lead bullets. I revisited the 25-20 and found that the standard chamber for it has no throat at all, and a very steep bevel into the rifling. No wonder it wouldn't work! I attacked it with a normal 25 caliber rifle throating reamer, which allowed the bullet to seat out of the case about .100" and have a chance at being aligned with the bore. What a difference! Suddenly I just about couldn't find a bad load for it, the thing would shoot well with everything I put in the chamber. Plain base or gaschecked, smokeless or black, it didn't matter as long as things were within reason.
Of course you can't do this with a lever action rifle because of the overall length considerations. But with a single shot, it works to really make them come alive. I eventually sold that barrel to somebody who needed it more than I did, so I no longer have a 25-20. I still cast the bullets to paper patch for use in a 6.5mm TCU and they work great there, and some day I plan on building up a Remington 580 to take 25-20, but that's after a lot more projects get completed first!