Hello
In WWII the big guns on battleships and cruisers were measured in inches like the Yamato being 18 inch guns and the USS Iowa being 16 inch guns.American ,French , Italian and Soviet tanks barrels were measured in mm .Now what gets me is British tanks where the power of the main gun was measured in pounds like 2 pound gun rather than MM so
how big is that exactly in terms of MM or inches is a 2 pound gun or was it a weight scale instead with any sized barrel?
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Interesting item: The English 25-pounder and the German 88 were of essentially the same bore size, a fact that Allied propagandists missed out on entirely (88mm vs. 87.6mm). The english placed the 25-pounder gun on a number of SP-chassis, but never developed it into a proper tank gun. The 17-pounder (76.2mm, or three-inch) gun was placed on any number of tanks, and gave the Sherman tank a much-needed boost in firepower.
Tha Austrailians worked on 25-pounder armed tanks, but dropped the plan when American tanks came available in large numbers.
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You learn very quickly in studying gun ballistics that bore size is nearly irrelevant in these sorts of things.
The 25 pounder was an artillery gun. The SP chassis (what’s the plural?) were mobile artillery pieces. The muzzle velocity is somewhere around 450 M/S… appropriate for artillery, but laughable as a tank cannon. The german 88 (there were quite a few models) ranged from about 850 to 1100 M/S.
Probably a stop gap measure. Although they did make AP rounds for the 25 pounder, they were mediocre in performance at best.
Btw, to the OP:
This goes back to British tradition… back to the ship-of-the-line days. They would measure a cannon by weighing a spherical cannon ball that was the size of the bore. So if the cannon fired 15 pound cannon balls, it was called a “15 pounder”…
British tanks were originally developed by the Navy, and so they took on naval nomenclature. That’s why tanks have a “hull” and such. So the “XX Pounder” tradition held throughout the years.
If I remember correctly, the 2 pounder was a 40mm gun, the 6 pounder was 57mm, the 17 pounder was 76mm, and the 25 pounder was 88mm. Beyond this size, they used the MM or inch designation. (4.5" guns, 5.5" guns, ect.)
Except when you’re talking propaganda, which is almost by definition aimed at the topically uneducated. The Allied propagandists missed the similarity in bore, as related to the AT role. It would’ve been quite simple to spread the word that, “yes, there is the 88, but we’ve got one too, and it kills tanks, just like theirs”. this wouldn’t have been strictly true, but would’ve been close enough to score a few morale points.
Actually, the DAK rather feared and respected the 25-pr, and would retire their tanks to allow their own 88’s and long-range machinegun fire to work-over the 25-pr’s positions. Germany placed whole battalians of captured 25-pr gun/howitzers in service along the Atlantic Wall. The 25-pr, while never originally intended as an anti-tank gun, did a fine job killing tanks, despite the unsuitability of it’s velocity for that role. The real trouble with this was that while gunning for tanks, the gun was unable to meet it’s primary responsibility of providing infantry support. Further, being placed in the AT role, many guns were destroyed, or over-run and captured. In Africa, the English lost 600+ 25-pr guns in this manner.
(from links posted above)
It was reported that in at least one instance, one 25-pr AP shell penetrated two German tanks, retaining sufficient energy to do damage beyond the second tank. While the German 88 gun was a superior tank killer, you must also remember that much of it’s velocity was pure over-kill (especially early in the war), being that the gun was a dual-purpose weapon, originally intended to shoot down high-altitude aircraft (hence the high velocity). The 25-pr gun/howitzer had plenty enough energy to kill tanks, and the only thing stopping it’s further developmant as tank main armament was the advent of the superior 17-pounder AT gun.
Actually, it was purpose built, incorporating American, British, and home-designed elements. It came complete with molded lower hulls and turrets, an Australian derivation of the US M-3 gearbox, and welded upper hull. Along with the ACII (2-pr, with built-in provisions for the 6-pr AT guns when they became available in quantity), the ACIIIa (17-pr), and the ACIV (17-pr), the ACIII (25-pr) was purpose built and designed by Austrailian industry to meet their local needs, using locally available alloys. It was the most complex undertaking of Australian industry up to that point, and represented a major accomplishment. Unfortunately for the future of the Sentinal tank, about the time when productions units started rolling off the line, the Allied tank shortage had been solved, and Australia began recieving obsolescent M-3 Grant tanks in quantity. The Australian gov’t put the AC Sentinal on hold, where it quietly died.