If you know how to remove pitting from barrels safely you can alter the POI by manipulating the material at the muzzle. This coupled with the right wad and a slower burning powder can go a long way to making the gun shoot better. There is a lot of trial and error and lots of trips to the pattern board. I have done this on two guns that I dearly loved but couldn't hit the broad side of a building with.
Both barrels shot low and a little right at 30 yards. If you are careful it is not visably noticeable from the outside or inside of the barrels. You will need wall thickness gauges to make sure you have enough material to work with.

"As for me and my house we will shoot Damascus!"