There also exist many AR-15-pattern rifles in the civilian market - obviously without the full-auto and burst-fire modes one finds in military models, but otherwise quite similar. They're generally satisfactory firearms - cheap to feed, not unpleasant to use or overly difficult to maintain.
They're also a longstanding bête noire of the anti-guns crowd, among whom the type is infamous because people have used them in a few mass shootings, and also because if you're afraid of firearms already then this type looks super extra scary - dressed in full tacticool ribs and Picatinny, it looks like something a Terminator might carry, and they're usually finished in black.
See I thought that was the M-16; I could even have told you "the civilian version is the AR-15 and doesn't have full auto" but I'd never heard it called an M4 before. (Speaking as someone from a non-gun country whose only exposure to any of this is popular culture).
There's a category for cheap, small-caliber pistols, "Saturday night special".