What you use to clean your barrel depends on the powder you use. Triple Seven is an ascorbic acid-based powder, so the residue left in your barrel is water soluble. I have used it since it came out, warm water patches followed by dry ones and a lightly oiled one is all that is required. I have never had ANY corrosion in my barrels.

Pyrodex or BP is not as water soluble, which is why people add things to help get the fouling out. Pellets of all kinds also have some real BP on the base to help them ignite so even Triple Seven pellets may require cleaning like it's BP to get it all out.

BH209 seems to be a nitrocellulose-based powder like modern smokeless. So you use similar solvents.