Why Britain did not standardize very heavy naval guns in the 1780s

What if Britain began producing 40-pounder naval guns in the 1780s?

Britain already fielded 48-pounders and moved away from them because slow fire and heavy ammunition outweighed the extra shot weight.

Britain had already used 48-pounder cannon, heavier than the proposed 40-pounder. Their slow rate of fire and the difficulty of handling such heavy ammunition explain why they were abandoned. A heavier shot therefore brought practical costs for the gun crew. The later 68-pounder aboard Warrior provides a comparison with another period of British heavy-gun development.