What they are
Raiders hold lairs and patrol at night. They are drawn to camps with a lot of machines and stores, so a big base brings them. A closed house keeps its light, noise and smell in, so it draws fewer.
Beating one
The rifle comes up and its muzzle glows before it fires. A step aside dodges the bolt. Raiders are armoured at the front, so get around the side or behind.
A raider always leaves weapon parts, iron scrap and leather, and now and then copper scrap or a lump of iron ore. Rarely there is a small trinket inside: copper scrap and a bead of glass.