I suspended my shotgun barrels from a coathanger over a rafter in my garage. I then heated the barrel from the (bottom)muzzle end upward with a propane torch. I kept heating the barrels with a sweeping motion as I applied the B/C plum brown solution using Q-tips.
Since heat rises, heating the muzzles which were at the bottom of the suspended barrels let the heat begin to warm the barrel up before I moved the torch up to bring the steel up hot enough to take the brown. I did the barrel in 4-6" sections, working from the muzzles on up to the tang. I swept the torch over this area of the barrel, around as much of the barrel as was exposed, doing one barrel first, and then returning to do the second barrel. Browning the rib was very quick to do, last.
This can work better if you have a helper moving the torch, while you hold and rotate the barrels using a pencil or other wooden stick in the muzzle to protect you from getting burned. This gives you better control over a suspended barrel, while you lather on the solution. I would use one of those disposable paint brushes, or Cotton balls held with needle-nose plyers the next time to do this. I was too tentative with my first effort.
It seems critical that you keep the barrels hot enough for this solution to work well. Removing the barrel from the heat source begins it cooling, which can give bad results fairly quickly.
My preference for the product is not based on the ease of using it, altho that is certainly a benefit, in my judgment. NO, I like the product because of the deep dark color I get, and its toughness. Used with oil that is also burned into the surface, the browning has provide very durable. :hatsoff: