Still full of scammers, unfortunately. Location: MASSACHUSETTS, MASSACHUSETTS is a pretty good sign it's BS as well as a listing with little or no personal tone or real-world expertise written on the gun. If it looks like it's written by someone with engrish as a third language stay away.
Found a 556 SCM on classifieds for $1100 about 1.5 years ago, almost bought it - bought the MCX Virtus instead for around $1700. My buddy bought the SCM though, having shot both, the Virtus was obviously a slightly stiffer shot being piston driven - SCM is a delight to shoot very soft recoil...
My dog, unfortunately, has episodes when he hears the c02 PST! PST! PST! out back even from inside the house. He really was shitting himself when I was doing baseboards and crown molding in the house last summer.