When I started shooting black powder I wore out a barrel in a very short time, and so did several of my friends. I now believe, that the majority of the wear, came from the cleaning process, not the act of loading, and or, shooting the gun. Back in the dark ages ( when all of our hair was dark) the old timers insisted on a cleaning regimen, that was long, and tedious, at best. Us newbies, regularly joked, about shooting for a day, and cleaning for three. With some of the modern metal preservatives that are readily available at the local big box stores, getting every microscopic speck of fouling out of the bore is not as important as it once was. Such mundane products as antifreeze, or WD40, stop rust at least for the short term. I only use WD40 in my smooth bores, but antifreeze is a major part of the cleaning solvent I use for cleaning in the field. It works great. You do have to remember to dispose of the used solvent as you would anti-freeze of course.
Hungry Horse