[Unclenick]

Svet,

He is referring to a steel-filled epoxy that has fine steel particles in it. Because they are surrounded by the epoxy resin they do not react with plating solutions correctly. Their main advantage is they have nearly the same linear temperature coefficient of expansion as steel, so they adhere to it well and don't tend to pop loose.

You are correct that solder does not blue by traditional methods. Traditional methods react with iron to form ferric ferrous oxide (magnetite) to get the blue/black colors. Solder has no iron in it to make this chemical reaction. There are cold blues for solder, but if you can't import GunKote, the chemicals, which include selenic acid, are not going to be easy to import either.

The restorers use TIG (not MIG) welding for filling steel. This is slower and at lower temperatures than other forms of welding, but gives the most control and allows you to choose the filler material. So you can buy steel wire of the same type alloy (or close to it) as the original gun metal and get good similarity of color later. The filling will overflow the pits, and you will have to have a means of reducing the surface back down to original dimensions. This is easy to do on the flat surfaces by gluing sandpaper to plate glass in successively finer grades to restore the desired finish. It is more difficult on cylindrical objects without a lathe. Cylinder flutes and your barrel contour might require grinding points on a milling machine to profile correctly. It is a lot of careful work.

If I were you, and didn't want to put a lot of money into it, I would consider finding an electroplating company who can lay a thick plate of soft metal evenly on the surface, then file and sand that flush with the original surface. The soft metal is to make it easier to file and shape. Have them use copper or brass or some other metal with a color you can distinguish from steel, so you don't go too deeply with your material removal. When you have the surface the condition you want, have them plate it with nickel, so it looks like an original nickel plated version of the gun. If you don't like nickel, you can get a black nickel or a black copper plate put on at the end.

If that proves to be too much expense where you are, then all I can suggest is using the steel-filled epoxy and sanding it flush, then painting it with an air brush using a 2-part flat black epoxy paint that you can bake hard afterwards. All slow-setting epoxies seem to respond well to baking at about 60-65°C overnight to harden them. You might be able to get some blue to mix with the black to take the "soot" appearance down. You would need to experiment with this on a sample. Many boat and marine suppliers have 2-part epoxy paints, as do “hobby” shops for model builders in this country. This may also be true where you are? All U.S. made spray-on gun finishes are likely to have too many nasty solvents for shipping overseas. MEK(methyl-ethyl ketone) is a common one. The only exception I can think of is some form of powder coat finish, but you need the right oven for that, and it wouldn't resemble any original gun finish from your gun's historical period.

Good luck with it.

Nick