Here is a built and detailed Ship mounted "Naval Cannon". It is 5.25"  long, 2.5" wide.

Metal rims on wooden wheels.
The all brass barrel is 4.5" long.

Some thread tie-down lines need to be re-tied.

The built model cannon is on a 6" by 4" beveled edge display wooden stand.

Perhaps you would like to add this piece to your Model Cannon collection.
Thanks for looking !