Texan: I don't know how you have tried to put on cold blue, but I have had success doing it my way. I have used 44-40, BirchwoodCasey gun Blue, someone's paste, and others, but they all needed help.
After cleaning the metal on the barrel with alcohol to remove all oils, I use a propane torch to heat the metal up to boiling temperature, so that a drop of water, or sweat beads and steams off the metal. I then use a Q-tip or two, dipped in the bluing solution and apply it to the hot metal. It sizzles and stinks, but the surface starts turning black. I will use a rag held in a gloved hand to brush the crusting off the surface of the metal, and then re-apply the heat and repeat the process.
Depending on how it looks in comparison to the factory blue I am repairing, I may repeat the process 4 or 5 times before I think I have the color right. Then I do it one more time. After wiping off the off-white colored crust, I spray the hot metal with Rem Oil. to both cool it, and close the pores of the steel. I leave the metal to hang bathed in the oil over night, to let the chemicals set. Then I wipe off the oil, wash the barrel in water, dry it, and take it out into the sunlight for inspection. If the color is even a little bit off, I repeat the process, until you can't see any difference. I have found that using oil to cool the metal helps to blacken the finish, and to make the finish stay deep in the metal. It holds better than cold blue rubbed on a cold surface.
I am not claiming it is as good as Hot blue, but you can make adequate repairs to small blemishes on metal with my method. I leave the metal sit for a couple of days in as much oil as will stay on it. I found that the longer it sits with oil the longer lasting the blue seems to be. During use, I handle it, clean it, and oil it, the same way I do with any gun.
One shotgun I used heavily needed to be reblued after several years, because of all the salts that got on the action from my hands. But that was how long the factory finish lasted under the same usage. Other areas of the shotgun that I did not touch were still in good shape, and didn't need any rebluing.
