I have a 1925 British pigeon gun 3" chambered with a proof shot weight of 1 1/2 oz.I know enough to not shoot 3" magnum loads in it because the old 3" live pigeon load was a lot lower pressured load.
But that gun will eat any modern 2 3/4"load, right ?
O.M
No. US (SAAMI) pressure standards are the same for 2 3/4" and 3" 12ga. And the maximum standard service pressure for American 12's is higher than that for vintage British guns. You'd be OK if you had a Brit 12ga with the CURRENT superior (magnum) proof. But not with that gun. One reason the British proofhouses changed from the 1925 rules to the 1954 rules (the ones that used "tons per square inch") is that between those two dates, British ammo makers had begun producing higher pressure loads which weren't available when the 1925 rules of proof were established. Prior to that time, all British 12ga 1 1/8 oz loads, for example, were OK in any British gun proofed for 1 1/8. That had actually changed before WWII with the appearance of hotter loads, but they didn't get around to modifying the proof rules until after the war.
