I’ve been a student of World War II history for most my life. Lately, I’ve found myself incredibly interested in the tanks that fought in that war. I’ve noticed that when it comes to identifying types of cannon mounted on tanks, the US did it by the bore of the cannon in millimeters - the 75mm cannon was mounted on the standard Sherman for example. But the British describe their cannons in pounds. They mounted their 17lb cannon on the Sherman to create the Firefly class. What exactly is this weight refering to? It’s obviously too low to be the weight of the cannon. My guess is that it’s the weight of the shell the cannon fired. If this is so, would this be just the weight of the projectile or the weight of the whole shell -cartridge and projectile- when it’s loaded into the cannon?
The designation ‘25 pounder gun’, for instance, means that the standard HE warhead for the tube weighs 25 pounds. The Germans would have called the same peice a ‘88’, as the actual muzzle caliber was 87.9mm (something like that), and the Americans would have called it either a ‘88’ or a ‘3.5 inch’.
But the weight designation referred to the actual projectile only, not the powder charge.
Thanks much!