My first LEGO Technic Moc. It's supposed to be a sniper rifle! It isn't able to shot or anything, but it does have som features like a trigger and a reloading system! :
LEGO Machine Gun Working - YouTube
LEGO MOC Automatic turret by kueden | Rebrickable - Build with LEGO
Lego guns and their mechanisms
LEGO MOC Anti-Aircraft Gun by kueden | Rebrickable - Build with LEGO