Upvote:1
This appears to be a Canadian 4.5 inch Howitzer Shell Mark IX, possibly for naval use. It is lacking a fuse and the low weight indicates it is also lacking its filler; that means it's inert.
Note the narrow copper band at the bottom and the lack of a boat tail (narrowing at the bottom). There's no space for a fuse at the bottom, the fuse would screw into the top and is missing.
For more information, try contacting the Canadian War Museum.