Setting: present day Montana, USA My MC is ex-military (US Marines, 4 tours of Afghanistan) and then an LAPD officer (now homicide detective). He's out of LA and has just been in a gun battle with some militia types. I want him to have the knowledge that a competent Marine/cop would have, but not be Mr. Wizard. And I want my militia to be very well-armed, definitely into the realm of illegal weapons, but not to the "backpack" nuke level. So, while looking at three dead militia men, still in a fairly combative situation, what would he be able to observe about their weaponry without deep investigation? I've already figured they'll have an M32 grenade launcher, and it's distinctive enough that I assume he'd be able to identify it at a glance. But for the other weapons? My cops have M4s in their cruisers, so they'd know that weapon well, even without the military background. Would my guy be able to tell at a glance that the militia were carrying M4A1s rather than the simple M4? Or if they were carrying other rifles, maybe the type that can be configured for semi-automatic or automatic firing, would he be able to tell at a glance that these were automatic, and therefore illegal? Are there other distinctive weapons that would be useful for militia to carry, assuming they'd just gotten a shipment from their illegal weapons supplier? Thanks for any help!