I agree with Mike.
It seems to be a fairly tough epoxy (alkyd) coating with respectable resistance to solvents and heat.
I've used it to coat an el-cheapo "beater" AK47 and the finished product had a nice non-glare quality to it (I used a matte black formula) and even color, that approaching 5+ years, shows little wear or degradation despite exposure to high heat from rapid and prolonged firing sessions.
It certainly strkes me as being alot tougher than most of the commonly encountered AK finishes which dissolve and run off if you even mention the word "solvent" in their presence. Made the rifle look like a million bucks, too.
I doubt, however, that it'll stand up for long to much metal on metal impingement since it is not really intended for that use. Like Mike said, I'd stay clear of "internals" and just apply it to exterior surfaces.
Without knowing what gun you are using it on (I am not asking either, since it is none of my business) it is hard to estimate what success you'll have with it.
Just make sure that you allow it to cure for at least 24 hours before handling it since it is really fragile and easily damaged until it is completely cured. I usually wait for at least a week from the last applied coat, but I might be being a little too obsessive about that.