dog,
Yeah, it's real...I own one in a 4" bbl. Bought it in 1990 in Fayeteville, NC at Jim's Gun and Pawn. It was brand new and he only had one other which was a 6".
Later that year on Ft. Bragg, there was an equipment expo in the Officer's Club with focus on selling stuff to ARSOF. I went over there and spoke with the S&W reps. They said around 5000 were manufactured (it could be lower) and they quit making them because any imperfections in the final polish (prior to blueing them) really showed up.
Mine only has a couple of places that show though and has done real well regarding holster wear. I shoot IDPA SSR with it occasionally, using a Blade-Tech Kydex holster.
The Performance Center did a really nice duty action job on mine as well.
IIRC the shop had it labeled as a "MIDNIGHT" or "MIDNITE" finish, but that could have been BS.
The box (yeah, I've still got it) lists the following: Model 686, product code 104250, Spec Ord 8346. There is an "M" designation on the top right corner of the white label on the box end.
That's all I know...wonder what these puppies are worth now?
Stay Safe...
Mike