Since that is exactly backwards to the way a gun is designed.... at least as far as I understand artillery, this being that one designs the base shell first and then builds the gun and propellant load around it, I would like to comment on that test.That's false; manufacturers, for shells at least, used whichever system was desired. The 1886 La Spezia armor trial was explicitly done with a BL 16.25" gun (made by Armstrong) with a Krupp shell (page 13), probably to get the most powerful gun/projectile combination possible as a benchmark to prove that the armor was completely immune to any existing gun. Manufacturers would happily make shells for whatever gun a customer used as long as they got paid. I suspect they'd make whatever gun calibers were desired too; there are plenty of cases in WWI of captured French 75's and other guns being rebored for German calibers, so manufacturers could probably do that from the factory with naval guns too
The people who ran that test were allegedly trying to weapon proof (er… armor proof) plate for coast artillery gun mounts for La Spezia, the Italian naval base. The mounts were supposed to be the landed gun houses for the mounting of a pair of Krupp 40 cm (note the metric bore diameter?)/L27 naval guns that operated with brown powder propellant, this being 1886. Now this was SMACK in the middle of a guns/armor race between the Italians and the British. I'm pulling this information from a book entitled
"Textbook of Gunnery" by Major G. Macinlay R.A. , Printed by St Martins (1887 edition)
and also the article in Scientific American about the British BL 16.25 110 ton naval rifle tests.
SCIENTIFIC AMERICAN SUPPLEMENT NO. 586; NEW YORK, MARCH 26, 1887
Firing Trial of the 110 1/2 ton Elswick Gun
The Grauson plate test was a one-off Sheboygan to specifically test expected maximum BRITISH gun performance against the contracted German cast iron plate that was to be the face plate on the fortification. It was a "special" that did not correspond to the general overall naval trends of the various technologies I discussed.The following figures are authoritative: Length over all, 524 in.; length of bore, 487.5 in. (30 calibers). The breech engages in the breech piece, leaving the A tube with its full strength for tangential strain (vide Fig.). The A tube is in a single piece instead of two lengths, as in the case of the Italia guns. It is supplied to Elswick from Whitworth's works, one of the few in England where such a tube could be made. There are four layers of metal hoops over the breech. Copper and bronze are used to give longitudinal strength. The obturation is a modification of the De Bange system, proposed by Vavasseur.
It was also a form of RUFUS waving, if you understand my meaning, in which Rome was telling London: "Mine is bigger and better than yours." Wholly impractical was the net result... as Sir George Tryon also discovered when he drowned on HMS Victoria.
This is to say, that you "could" in a war emergency during an ammunition shortage, take 50,000 captured German 7.5cm APCBC shells and by changing the banding on a lathe in Egyptian field depots and doing some propellant case annealing, also, fit the thoroughly bodged shell such that you could ram the "cartridge" through and into the breech of a US made M2/M3 tank gun on a Lee/Grant and return it to its original makers to knock holes in PZKWIIIs and PZKWIVs. Yes; you can do that thing in a war emergency, but Murphy what you do to the expected shot life of the gun!
These idiocies, the Grauson armor proof and the 8th Army emergency shell modifications before El Alamein, would possibly meet the severe disapproval of Major G. Macinlay of the Royal Artillery?