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
MOC] 100% LEGO Automatic Gun - LEGO Technic, Mindstorms, Model Team and Scale Modeling - Eurobricks Forums
LEGO MOC Automatic turret by kueden | Rebrickable - Build with LEGO