Q&A for How to Blue a Gun Barrel

You can use any bluing solution, as long as you make sure not to get any on the inside of the barrel. If you are planning to hot blue it, you should plug the ends of the barrel so that no solution can get inside. You can also cold blue it, using Birchwood Casey Super Blue or Perma Blue. This won't offer as much protection, but it does require less equipment and ensures that none gets inside the barrel.

There are different solutions on the market. "Du-Lite" is a commercial solution that is sold to professionals. It's also used by gun manufacturers like Colt or Smith and Wesson. Cold blue solutions usually use a caustic solution that "rusts" steel to turn it a blue-black color. It's then neutralized with another solution and washed with hot water, then oiled.

No "bullets" come out of a double barrel shotgun. Most double barrel shotguns fire one barrel at a time where you need to pull the trigger once for the first barrel and a second time for the second barrel. Some shotguns can fire both barrels at the same time. The recoil is brutal.

Cold bluing will ultimately look much better, but the spray paint approach will be less costly and less time consuming.

Make sure there are no fingerprints or any kind of oil or smudge on the metal. Degrease the metal and then heat it up with a small pocket torch to the area turning blue.