This is an interesting thread. I bought an M39 a few months ago from a private seller, $250. It came with an extra M91/30 bolt, a rear sight base tube, and upgraded trigger plus original trigger, and tool kit. The bore is bright, and the metal is surfaces are very good to excellent.
The stock appears to have been refinished, and has a rather unusual, light colored finish, almost blond, with some darker areas, a couple of inches in size, here and there where maybe stain was concentrated during refinish? Also, who ever did refinish, applied a medium gloss surface. So, the stock isn't original, but it doesn't look bad, just unusual.
I am not sure whether or not to use .308 or .312 diameter bullets, have tried both at about 2500 fps velocities, both group 2" at 50 yards...I'm going to slug the barrel this weekend to determine bore diameter for sure. I believe it is capable of better accuracy if my eyes were up to it!
Because of my old eyes, I've installed a Mojo aperture rear sight, which helps me a lot.
I'll post a photo or two, and serial number & markings info soon.