For sure! Soak in apple cider vinegar, brush with wire brush, tap with the back of a spoon to remove rust, soak, brush, tap, etc. until all the rust is gone. Then coat with briwax or heat the oven and coat with crisco. The last gun barrel I did, I poured rust converter down the inside of the barrel after I had treated the outside of the gun. (I like a less shiny finished product for my iron relics).
Congrats on the gun barrel!
Post in What is It after it's cleaned and I'm sure someone could narrow down the make/model. Include the diameter of the barrel, barrel length, and close-up of the butt end of the barrel from several different angles.
Cheers,
Buck