Miller,
Based on my own experience, I would say that Oscar was NOT wrong. I recently had a gunsmith friend who has a hot-blue set-up(I do not), blue the barrel assembly of a double rifle for me. I had built this rifle, so I know for a fact that the only solder used anywhere in that barrel assembly was Hi-Force 44.That excludes the brazing metal which had originally been used to join the barrels at the breech end. He had some trouble achieving the desired level of blue, and consequently the barrel assembly stayed in the tank for about 45 minutes. There was a considerable amount of the Hi-Force 44 eaten away around the keel between the muzzles, which I had to repair later. Based on this experience, I'm going to stick to my rust bluing and would never again trust a double to a hot blue tank.
