Details

In the T2K Small Arms Guide the M16A2 they show has some, oddites.

There's no groove for the charging handle latch.

There's a retaining pin for the buffer retaining plunger.

The lower doesn't have the reinforcement that an A2 lower should where the receiver extension screws in.

The markings say "CAL .223" instead of "CAL. 5.56 MM." and "MODEL SP1" but do not say "PROPERTY OF US GOVT."

Like my clone, there is no pin for the auto-sear despite being marked for burst.  Also, like my clone, that's a semi-auto hammer.

The upper has the distinctive "shelf" for the cut-away half-moon bolt-carrier that kept SP1 owners from being evil and converting them to full auto.  It also has the SP1 screw at the front instead of the more normal captive pin.

Some details of the rear sight and handguard make me think the artist was working from a picture of an A1 style SP1 and they used artistic license to change them to resemble M16A2 parts.

That author drew over several photos that I've found later to make them more T2K from the original sources.  Several Vietnam photos got that treatment, his "kevlar" helmets are obviously M1 pots with skirts added than the real deal.