I had an Idea last night, I figured you could get some coarse sandpaper, wrap it around a steel or aluminum rod and secure it with some tape so it's tight in the bore, then put it in a drill, slowly run it down the barrel, switch it when it gets dull and clogged, and basically sand the rifling out. Then maybe get some fine sandpaper, polish the bore so it's nice and shiny. Basically sand away the lands all the way to the grooves so you basically have a smoothbore. It shouldn't be significantly weaker than it was before given it only lost the lands.
I have been considering reaming the rifling out of my gun, it seems to throw fliers and I could probably get better accuracy with a smoothbore. Not to mention I could also shoot buckshot, birdshot, buck and ball, and round balls with decent results. I could probably even make sort of a foster slug or a Brenekke slug using a Minne ball and a wad to seal the gasses behind it if I wanted to shoot conicals. I figure since I'm buying the exact same rifle as a kit in percussion that could be my gun for Minnie balls, and the original rifle could be my smooth rifle to shoot shot and ball with. It's starting to really appeal to me, I shot a paper target and realized that my fliers were actually too frequent for my tastes. I think making it into a smooth rifle would actually be pretty cool, I'm going to sleep on this and consider the trade-offs.
~Levi