Something else I might throw into the discussion. In the post I made linking to various pages on DevianArts held by designers of concept weapons, one of them (Linked below.) is to a weapon that by it's
appearance and color scheme (Which recalls many common types of multimeter/caterpillar tractors) appears to be an industrial weapon rather than a military one. It could be that some companies make their own weapons and issue them specifically to their guards
or for sale to other industrial/financial concerns further down the economic food chain.
The weapon itself is linked below: