Jorg,
There is no risk involved. I got the idea from Dixie Texian, a THR member, and it works.
De-blueing is as easy as eating a ham sandwich.
Put the metal in household vinegar and the blueing just dissolves, 15 to 20 minutes is all it takes and it does not damage the metal any which way. It's hard to believe it is this simple, but it is.
Note: I have heard the blueing residue is poison. I de-blued in my frying pan and made sure I cleaned it up real good afterwards.
The browning is done by heating the gun to a temperature so a waterdrop will boil on the gun. Try to heat it up with a flame evenly so things will not warp, don't know if this could happen but I like to stay on the safe side.
Then, immidiately after heating, wipe with a sponge with some birchwood Casey Plum Brown barrel finish.
You should hear a 'Tsssssss' sound (the gun part your are about to treat is hot remember?) as you touch the part with the sponge, and the rust is instant. Wipe the sponge along the gun, do not tap, this did not give me an even finish. If the gun does not hiss when you touch it with the wet sponge it is to cold and you should stop and re-heat. If you are done with the part rinse thougroly in water so the Plum Brown acids will dissolve.
You may want to use gloves, I didn't but there are acids in Plum Brown.
Try not to get it inside the barrel or chambers.
Then gently 'sand it down' with this steel wool. I used 000 grade, 0000 grade is the finest but could not get that. This steel wool stuff leaves no scratches and the rust removal will go slow and fully under control.
Check out my site for photo's, it is in the Dutch language but photo's tell a lot and maybe give you an idea what to expect.
Again, it not so difficult. If it was I could not have done it, I am not handy and actually well below average.
There is nothing to hold you back.
http://www.twolefthands.nl/Zwart Kruit/page10/zwartkruit10.htm
You will have to scroll down a bit to get to the Walker section.