[35NCO]

Using the flash hider or even the weapon would not be a good way to judge. Weird weapons that don't belong turn up all over the world all the time in places they should never be. Sometimes as well people have weapons they should not have intentionally to give the perception they are someone else.

Plausible deny ability, covert, foreign copy's, old US sales, or just some arms dealers and drug runners...anything can place a weapon anywhere. That goes for all sorts of other US equipment and vise-versa to other nation states equipment too.