There are lots of ways to clean shotgun bores. Two of the poorest
are with Tico Tools or Bore Snakes. Either one might make the dirty bore look smooth but will not likely be really clean. A simple way that works very effectively for me is an aluminum cleaning rod, chucked in a variable speed electric drill, a stiff bronze bore brush wrapped with 00-0000 steel wool. Shoot a bit of your favorite bore cleaner down the bore, run the drill-powered brush in and out slowly, one time, and you're done. Push a patch through each hole with your favorite preservative on it and you've got a completely clean and rust-protected bore. Takes about the same time as it took me to type this.
Helpful hints: Removing the cleaning rod handle makes it easier to chuck the rod into the drill motor. Clamping the barrel lump into a padded vise makes the job easier still.
Does anyone else ever wonder why choke tubes collect plastic far more than fixed chokes do? Anyone know why?