welcome to the forum, and as noted above definitely aftermarket due to the color ,my guess is chrome, and the prep work beforehand leaves a lot fo be desired, reminds me of an old Colt 1911 my brother in law stationed out on the coast had done, I believe in Tijuana, lots of cross hash marks in the metal surface, still a nice piece, and back then LOTS of old guns ,mainly wartime bring homes were done in bumper shops across the country ,,,can always tell, as chrome is white and nickel is yellow.....again, nice piece, it is what it is, and would be a neat back packing ,trail gun.......
need to add for the term "coin nickel finish" is an electroplated or electroless coating applied to firearms for enhanced corrosion resistance, classic aesthetic appeal, and a slightly softer, yellow-tinted shine.

such as the Ruger 12 ga.,Red Label, Ken Hurst engraved shotguns of, I believe 1984 , the "Duck Stamp Edition", wish I kept a picture of that, they were beautiful
