Grump,
First thing I have to say, is that I'm in Arizona. Pretty dry, typically. I hung wet rags up in my shop and kept the door closed for the twelve-hour period between applications of the solution. I kept the door open, though, when we had a nice three-day storm roll through here in January. That helped out a lot. If you live in a humid area, you probably don't have to use the rags. If your house is dried out (low humidity) because of your furnace running in the winter ( or a/c in the summer), you should probably use the rags.
It took me a good two weeks to get a finish. But, mine is not typical, as it took me three times. First time, I finished it with boiled linseed oil, and it looked horrible! Mostly it was my fault in not knowing how to handle linseed oil, but the end result was still bad. It took three hours with a quart of acetone from Ace Hardware and a rag to strip all of it off. I hung the barrel again, and re-applied the solution for a second period of about 3-4 days, at 12 hour intervals. When it had reached the color I wanted, I tried (upon the advice of the people who had sold me the solution) simply applying Outer's Gun Oil to it, to finish it. It leached the rust out, perpetually lightening the finish.
Third time worked like a charm. I called Laurel Mountain Forge and asked THEM what to do, to finish it. They suggested that after the treatments were done, I 1) gently heating the barrel with a torch, 2) applying pure beeswax to the metal, allowing it to penetrate the pores, and 3) removing the excess (smoothing it, really) with a pair of old nylons. O.K., I rehung the barrel and furniture, and started applying the solution, going for a period of 5 days with reapplication every 12 hours. I also began calling around Apache Junction, Queen Creek and Tempe, AZ., looking for beeswax. Found some at a swap meet (where a bee keeper had a family stall) for $1.50. By the end of the process, after the wax application, it worked out beautifully and the finish is fairly durable.
There are some other things I did also. I was very concientious of degreasing everything on a periodic basis with either Birchwood Casey Gunscrubber or Acetone. This helped to ensure an even coloring w/o light spots. I wore rubber gloves (from the pharmacy or Wal-Mart) to prevent finger prints - they may or may not disappear with the use of the Browning solution - hence the extra precaution of the degreaser. I also, before the evening application of the solution ( I did mine at 8AM and 8PM), "carded" the scale off of the barrel using a rough cloth, in my case, a shop rag. You may have to use #0000 steel wool - I did after my second fiasco. If you do, degrease it also with acetone. The steel wool got rid of a lot of the harsh scale that the gun oil had leached out. But whatever you feel you have to use, card the metal. You will get a better surface out of it.
That's about it. It took effort and patience,but I am very happy with the results. I hope it works out for you too. Hope this helps.