cannon cannonball

Hello, So I have a question related to sustained firing. I was recently listening to an audio book of the Aubrey-Maturin series when they discussed reducing charge to avoid bursting or dismounting a gun based on the observation that the same charge produces more force as the guns heat up. Now...

Yeah, didn’t see any markings anywhere. Ideas or directions to head in would be great. Thx in advance. The cannonball pictured is not for this cannon. I feel the cannon could fire as it is sturdy and heavy. Just requires bravery.