FPS Rig (and Gun) is a free maya rig by Mattias Kirsten that includes arms, hands and a gun. Grab it from the bottom of his personal website
Alien FPS Rig
Alien FPS Rig is a free first person rig for Maya based on a sci-fi theme (inspired by Alien). Made by Guillermo Moreno Alfaro.
FPS Rig (AK47)
FPS Rig (AK47) is a free First Person maya rig that includes the hands, camera and gun. Grab the files from this google drive folder by Haydn Cooper