Lee Enfield Paint that Isn't
There are a lot of posts here and other forums about the black finish on Lee Enfield rifles models, particularly the No. 4 and later. It looks like paint but actually was not originally, although paint may have been applied somewhere along the line before you got it. The actual, original factory finish was "oil blackening" which is a coating of carbonized oil, like but different than parkerizing. Like partkerizing the coating itself was not corrosion protecting but a semi-porus vehicle or substrate to retain oil. Oil fills the porus coating, which provided the protection. Oil blackening is much the same thing as blackening cast iron fry pans by coating them in oil, baking them in an oven and building up a black carbon residue that protects the iron from rust as long as it is lightly oiled. I don't know the exact process the British factories used or the particular oil in a production environment. The temperature to blacken an oil is well below the temperature than would affect tempering of parts; probably 350 - 400 deg. F, depending on the oil as all oils have differing smoke points. The objective is carbonize a coating of oil on a metal surface. I don't know if they did it in one coating or multiple. One should be able to approximate the process in your home oven; if your wife will let you. Preheat the oven to temperature, coat the part with oil and bake it until the oil smokes off. Burnt cylinder oil smokes at pretty low temperature and already has some carbon content in it but will stink to high heaven. Any one of a number of paints, like high temp. grill paint, will give a near identical finish, but Enfields didn't come from the factory painted - according to my sources anyway. Thanks for listening and I hope this is a useful post.
