It's either a parts gun or a transitional AR15A2-
SP-1 lower
Old style, none tapered slipring
A2 barrel
Three prong flash hider
A2 pistol grip
Looks like an A1 buttstock, hard to tell from here.
The color difference between the upper and lower suggests an aftermarket or non-Colt upper, although by the hinge pin appears to be the large SP-1 type.
maybe they just pulled the photo from another source?