Your starting statement is mine except I only work on sxs that are mine, and like you I like doing it. Found out the rust bluing is not hard, the prep is the hardest.
For your first question, I start out with 220 grit emery cloth, if there was a lot of pitting maybe I would use 180 grit. Work my way down to 320 and on the last phase I only go in one direction and do not stop until end. I've also heard that you should use a block of wood. Next time I will. If there are any dents they should be taken care of first. I made up various tapered steel plugs 1 1/2" long and at other end it is bore size (.001 under) with a 1/4-20 threaded hole to hold plug. Lightly heat barrel with propane Bernzomatic and on plug you could use some high temperature grease. I lightly tap area with a small brass or plastic mallet until I can slide plug past area. On some Damascus barels with small dings you can sometimes tap plug and it will come out.
2. I use Laurel Mountain Forge Browner & Degresser. I find it works very well. On the Damascus barrels I use Radio Shacks printed circuit board etchant.
3. I made a plywood steam box to fit barrels up to 32" long and with wooden plugs in each end to hold them up during rusting. I put a small container of hot water (microwave) and let them sit for 3-4 hrs.(summer, haven't tried any in winter)
4. Follow the instruction on the bottle from Laurel Mountain Forge.
5. I boil for 5 minutes.
6. They (LMP) recommends to use demium or burlap. I use 0000 steel wool. Some use 0 steel wool,I think that is to harsh and you will scratch barrels in my opinion. I have never used a wire wheel but the experts do.
7. The amount of coats is up to you. I have done a few barrels wilth 5 coats and I think they look good.
8. They should rest for a while, a day, and then I heat the barrels with a torch and liberally apply motor oil, barrels shuld be warm to the touch but not burn you. Let sit and thoroughly wipe off, sit back and admire your work.
Most of the information here was from members that shared their knowledge.
1897 Grade 3 L.C. Smith. before and after.
Iver Johnson Hercules 16 ga.
Good luck and let us know how you make out.
