I always lubed the outside of the paper-patched bullet with a 50/50 mix of BW and Vaseline. It was soft enough to easily rub into the paper.

The barrel's throat and bore should be good for 15,000 to 30,000 rounds.

Ross Seyfried wrote a couple articles in Handloader magazine on paper patching jacketed bullets to increase their size where proper sized bullets were hard to find.
here is my patching board, set up for either .45 or .50 cal bullets. The groove, about 1/8" wide, allows the bullet and paper to start with a tighter fit together, than on a flat surface - at least that was the originator's intent and how it worked for me- and my brother. We both use patching boards. use of the board made it much easier for us to get a tight patch. The patch, is slightly 'wetted' and due to the cotton content, shrinks tightly to the bullet. I placed the 310gr. .375 lubed bulet on the board merely for effect. The steel plate is the patch cutting template wherein many patches can be cut at once - depending on the sharpness of the blade being used. Some people use an office paper shear, which also works very well.