Mk 37 Mod 0 Underwater Assault Rifle

The Mk 37 Mod 0 Underwater Assault Rifle, sometimes nicknamed the Frogman Stinger, is a fictional USA-made copy of the real Russian APS Underwater Assault Rifle 5.56 mm. The Mk 37 Mod 0 occurs in the fictional scenario of a "Twilight War" which happens in the scenario of the role-playing game called Twilight 2000. The Mk 37 Mod 0 does not exist in the real world.

This rifle is described in at least one external website, along with many real weapons, without enough markers or clues to distinguish real from fictional.