As Im sure many of us here have, Ive looked these pictures over now a considerable amount, and if i were a betting man, I would put $9.50 out of $10 of my money on it that is is a fake. Several machining shortcuts drive the final nail in the coffin, namely the "U" knock between the mounting screws, the taper in front of the front mounting screw, and the tapered cuts on several places including the mlok rails, pic rails, and under the center rail section. Id be interested to take a machining caliper (sensitive to .0000) to the mlok sections for consistency and size as well as the qd circle and rail sections. Also, anodizing is not a perfect science (just look at the differences in color and quality from major manufacturers) and even harder to get a good finish if you strip and re-anodize something. For the sake of seeing one of the most rare factory Geissele rails ever, Id love to be wrong.
I don't want to advocate buying fakes and certainly do not intend to advertise, so Im not going to put up links. But a search for fake rails will land you a spot on replica from China. And guess what the only length that are available in... 9.5". Both MK4 and MK8s Available in Black, fde, and ... bum, bum, buuuummmmm... od green. A local flea market in my area has a fairly large airsoft store and I've stopped in a time or two. The most recent time, Geissele rails on several ARs and AR416's, albeit no OD versions. Unless you had a real one in hand, you would SWEAR they were real. Gorgeous copies, but copies none the less.
What is more likely, that someone found an oddly machined Geissele Rail, chemically stripped the factory anodizing, perfectly re-anodized the rail in OD Green, then mimicked the factory lettering to a just passable degree in a programmer (but not exact), then re-lasered the factory markings, changing it to say "Federal" (in the wrong place) and just enough to reflect the actual length of 9.5" instead of the 10" the Federal rail is supposed to be???? Or, the Chinese copied it just like they copy EVERYTHING else only to make $4 profit, and steal any American's credit card # that is dumb enough to place an order on that God awful website?
Bottom line, I wouldnt trust a fake $25 Chinese rail and barrel nut wrapped around my barrel ... That is, unless that barrel was shooting 6mm bb's.