> I think Nelson got his range figures from one of Friedman's books. >
The 16,500 yards or 15,090 meters for the USN Mark II 7-inch/45cal gun on its original pedestal mount, permitting 15° max elev, came from the Naval Weapons website, which does reference both Campbell and Friedman. See
The 15,500 meters originated with the two Japanese officers who examined the Allied ordnance matériel on Java in 1942, duly translated in Monograph No. 68. Whether this figure came from the Dutch or was an estimate by the Japanese, I’m not certain. The difference between 15,090 and 15,500 meters is 410 meters or 448 yards or one-quarter mile, not much to quibble about. Normally, there is a not inconsiderable difference between the effective
maximum range and the actual
maximum range of a particular gun, thus a mere 410 meters is hardly such.
That written, my uncle served for part of WWII with D Battery, 8th U.S. Coast Artillery. That unit was armed with four 155mm GPF rifles (Grande Puissance Filloux, named for its designer, Col. Louis J.F. Filloux, French Army). As with others, my uncle said that the GPF was highly accurate to ten miles or a bit more, but then its accuracy fell off rapidly with any additional range attempted. The Tanignak collection includes a nice shot of the GPF on a 360° Panama mount, which adapted the French field gun to an American coast artillery piece having greater and quicker traverse, in order to track fast-moving enemy warships.