I agree with Neil Goeppinger that this is a ship bell. I have one nearly identical to it but with the US inset in the body of the bell rather than raised in bas relief. This was likely used on a WWII ship. Navy Bells usually have USN on the bell and I wonder whether it was from an Army Liberty Ship. Mine also says US and not USA or USN. The original mount for mine was cut off by the scrap yard that had the bell and was a cantilevered mount to allow the bell to be mounted to a flat bulkhead. It is most likely made of bronze since brass would rapidly corrode to a green patina in salt air and most ship bells were made of bronze.
Harry Long, MD