Everyday weapons?

As Rob notes, scale is a big factor.  If you're working in larger scale, there are weapons sets made for the 1/6 figures (12", or original-GI Joe-size) made by Dragon, among others.  You can also find weapons made by sci-fi/fantasy/anime kit manufacturers, things like weapons for Gundam robots, that, while their scale is given as small, like 1/144, they're designed for a figure that would be as tall as a 5-storey building in 1:1, and so, the weapons work in 1/20 through 1/25 or so.

In the car kit scales of 1/24 and 1/25, there are also figures out there, that you can modify for use with your subjects.  Your theme is a relatively popular one, actually.

You don't mention scale, most of these things are available in 1/35 scale as well as some pickup trucks by Meng to represent the ad hoc paramilitary equipment being used in current Middle Eastern conflicts.

In 1/25 scale, MPC makes a series of police cars that have been reissued time and time again over the years. Most currently as the Dukes of Hazzard sheriff patrol car and original Batman (Michael Keaton) Gotham City Police car/Joker Goon car. It includes a few civilian style weapons like a revolver and shot gun.