Check out Etasphera08 robot with gun Low-poly 3D model on CGTrader for $60. High-quality mesh by kasheydd: 47280 polys, 48794 vertices. Rigged, Animated, PBR.
UNITYPACKAGE (Unity 3D, filesize: 379 MB), UASSET (UnrealEngine, filesize: 441 MB), FBX (Autodesk FBX, filesize: 133 MB), MA (Autodesk Maya, filesize: 133 MB)