Top Dean,after researching original finishes I found that rust blue would have still been the most common refinish in the late 1800's. With much digging through old articles and web sights most describe using a tray long enough to boil barrel or barreled action in ,at least one said you could just pour boiling water over the parts but then I saw how steam would have been used originally. From there I found where someone wrote about using PVC pipe fitted over a pan of boiling water.                                                                                 While most small parts can be boiled on top of the kitchen stove,for the barrel I first found a pan that my wife was going to toss because of chipped porcelin.my first thought was to cut a piece of plywood to fit which should work for the short term then use a piece of 4'' schedule 40 PVC long enough to fit the barrel in.Note that thin wall pipe will start to melt,my biggest mistake but once changed worked great.The part used to adapt the pipe to my bucket or what ever cover you use is a toilet flange.The cover can be anything,I found that a little back pressure seemed to even the conversion faster.Also by leaving it uncovered and just warming the water it made a perfect humidifier for the rusting process.                                                                               What ever you do don't forget to protect the bore.If you want any more help just contact me,I can probably find the bracket I made to hang the barreled action straight in the pipe and take a picture of it.I was able to devote a lot of time that I couldn't normally but I was confined to the house after surgery.                                                                                John.