High poly model Machine Gun for subdivision ready 3D model is available on CGTrader for $10. Original author: artmyworks. Specs: 328310 polys, 330072 verts.
BLEND (Blender, filesize: 215 MB), FBX (Autodesk FBX, filesize: 431 MB), TEXTURES (Textures, filesize: 215 MB)