FWIW, the Eddystone/Winchester/Remington I picked up this month has that same black finish that looks like paint. The stock is well used but has no stampings or cartouches. The Eddystone bolt has that old greenish parked finish. The black coating has chipped a bit near the top of the rear sight ears but all along the barrel it looks like it was applied yesterday and the stamped inspection marks are clear and sharp and the 10-18 W mark is well defined.
I've seen a lot of parkerized firearms but never anything smooth and black like this other than some brass furniture on old Mosins that had been painted, yet that easily came off.