Good point Larry. I probably didn't word my post the best, it should have read proofed for a 3-ton load. As the guns themselves are marked 3 Tons it is rather normal to refer to them as a 3-ton proof, meaning, of course, the prescribed pressure level of the shell they are intended to fire.
Not truly that confusing as IF the guns had been proofed with only 3 tons of pressure there would have been no shells they could have fired & been "In Proof".
Unfortunately, the Brits themselves add to the confusion re proof vs service pressure. Quoting from a box of Gamebore Pure Gold shells:
"WARNING. Please note that these cartridges are suitable for use in: 65/67mm case length: Guns with a chamber length of 2 1/2" or longer, nitro proofed to a service pressure of 3 tons per square inch (850kg per square cm)." All fine until the very end, when the warning equates service pressure using the imperial system to proof pressure using the metric system.
Sometimes I think it's an evil plot to confuse us Yanks!
