It will not pit or do anything to the bronze other than tarnish it very slightly. Hitting the brass the next day with a soft cloth and brasso will have it looking like a million bucks. When I blue I use 3 pipe burners and 6 tanks. All tanks are stainless steel except the blue tank which is mild steel. 1st tank is dicro clean, heated acording to directions. Next is a flowing cold water rinse in my rinse tank which uses tap water run through a carbon filter and injected through a spraybar along the bottom of the tank and constantly overflowing to flush away gunk and keep from redepositing it on the gun as it is brought out of the tank. 3rd tank is oxynate 7 according to directions. 4th is back into the flowing cold water rinse. 5th is into a bleed out neautrilizer soak according to directions. 6th is into a hot water rinse tank. 7 is fully submerged and suspended off the bottom of a water displacing oil tank. If it sounds like a pain, it is. Is it worth it? I think so. I might not know a lot, but bluing watercooled 28's is something I have done once or twice.
It is not like parking, metal prep is of utmost importance and to do a good job you need at least 2 pipe burners and 4 tanks. The hardware required to do one correctly can easily cost as much as 4 or 5 of the watercooled parts kits.
The chemicals can be pretty dangerous to use and improper dunking can cause air trapped in the water jacket to create an eruption of 300 degree caustic salts. If you respect it with a mild dose of fear all should be good. Wear protective clothing and read everything you can get until you have memorized it. Brownells has some pdf files with instructions to download from their website and they are invaluable. It is a major ordeal, so make sure you are fully comitted to a blue gun before you take the plunge. If oow will blue it for you you will come out cheaper than doing it yourself, even if they charge 3 grand. It is rewarding to do it yourself and I am somewhat anal. I wanted my gun done a certain way and I could not find anyone to do it like I wanted so there you go. Take your time and explore all roads before proceeding down one. Blue guns are expensive and a path most folks wish they had not started down once the cost and maint. is realized. But to those few that like it, there is nothing quite like it. Good luck in your journey and keep us posted on your progress.
For the regulars, I am sorry to show these same old pics again. I will try to get something else before I post anymore pics.