Reports of Portuguese cannon breaking galleys apart lead to a comparison of nominal and actual shot weights. English and French 18-pounders are described as sometimes firing shot closer to 17.8 or 17.9 pounds. Portuguese examples are described as firing balls weighing about 19-20 pounds by the others' measures despite retaining the 18-pounder label. The reason for the difference is left uncertain. The comparison cautions against assuming that identically named guns fired identical projectiles.
Notable Point · 30:18-31:46
Why an 18-pounder label does not settle shot weight
Portuguese and Anglo-French 18-pounder labels are compared with the different shot weights reported for them.