This section is likely to contain major spoilers pertaining to the story of Project Zomboid.
Gun nuts are human (non-zombie) Non-player character survivors. They are hostile toward the player character, though they typically shout warnings before attacking. When killed they drop a shotgun, a baseball bat, 32 shotgun shells and a lighter.
There is a gun nut which the player may encounter toward the end of the tutorial. After the player listens to the radio message (and turns the oven off, preventing a fire), a gun nut will approach the side door of the safehouse and enter, tearing off any barricades. If not killed or attacked, the npc threatens the player and then directs them upstairs. After directing the player inside the bedroom the npc will claim that Kate Smith is infected, then despite the player's protests will shoot Kate Smith and the player. Should the npc miss or otherwise not notice the player, he will proceed upstairs to threaten then presumably kill Kate.
Inside of the grocery store standing between two aisles is a gun nut. Upon seeing the player, the gun nut will threaten them to step outside of the store. Failure to heed this warning results in the npc shooting at the player.