Help identifying shell

Need help identifying shell found in the water in casco bay maine. Maybe m1903 50 caliber? About 3” by 10” with flat base and conical nose. No markings left.

We really need to see a photo of the head (base) and the profile (side view) to be of any help.

I’m not convinced that it is ordnance yet. Can you take a picture end on from the base (largest diameter) and a second closer view of the nose?