I contend that a 1925 6-1/2 pound 12 bore Birmingham boxlock was designed to shoot, day in and day out, 1-1/16 oz at about 1,150fps and sub 9,000psi. It was proofed at about 15,000 psi if memory serves. It was stamped by the proof house at 1-1/8oz.
My little Chrysler Crossfire is capable of putting out 215hp and maintaining a top speed of 150mph. But it was designed for , day in and day out, cruising at 80mph and quick but not constant full throttle acceleration.
In the period guns I am interested in the British service load was always less than the maximum load. So a 16 was stamped by the proof house "1oz" but its service load was 7/8oz. A 20 was stamped "7/8oz" but its service load was 3/4oz. The 12 was stamped 1-1/8oz but its service load was 1-1/16 oz. This information is in a table in one of Burrard's three volumes.
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