$9 5-inch 50-caliber US Naval Gun 3D model by stefanotoneatto. Available on CGTrader. Check it out on CGHub.
STL (Stereolithography, filesize: 3.44 MB), OBJ (OBJ, filesize: 2.85 MB), BLEND (Blender, filesize: 25.2 MB), DAE (Collada, filesize: 4.03 MB), FBX (Autodesk FBX, filesize: 1.96 MB), GLTF (glTF, filesize: 2.53 MB)