The OP may have a cheap barrel not worth sending to a smith. Some years ago, I had a cheap H&R .223 that was left in a soft gun case and the barrel rusted. I bought a Blue Wonder kit and followed the instructions. It took quite a while to finish just the barrel. Think I made 16 passes. But when finished, it looked pretty darn good.
Smokestick, 1 vote for Cerakote. I had a .257 Wby done 5 years ago when I found rust after a wet hunt. The finish is still scratch-free and looks like new. The only problem with Cerakote is choosing from the vast variety of colors. Tough stuff
The bottom line,,, there's no fast, easy , cheap way..... If you view your firearms as nothing more than tools paint from WallyWorld will work. If you value them as more than that, spend a few 'bucks' and have the finish of your choice applied properly.