The Putilov-made Lender 76mm entered Russian naval service during the Civil War. Production continued until 1934. It was a 1903 light army weapon revived for anti-aircraft fire on a balanced mounting designed in 1913 (the gun was balanced roughly at mid-length). This gun was semi-automatic with a vertical wedge breech and a single recoil cylinder underneath. This example is at the Finnish national air defence museum. (Dr Raymond Cheung)
Designs for HA mountings for standard naval guns (75mm, 47mm, 37mm) began about 1914, and there were also improvised (and never standardised) high-angle mountings for 102mm/60 and 63mm guns.
United States
Beginning in 1914, the Characteristics (staff requirements) of US warships included ‘aeroplane guns’. Just before the First World War the navy chose the 3in/50 as its preferred anti-aircraft gun for large ships. BuOrd adapted both the new 3in/50 Mk X and an existing 1pdr pompom for anti-aircraft use (the latter was analogous to the pom-pom used by the Royal Navy). Although some design calculations for Mk X were dated March 1913, work on a 3in anti-aircraft gun seems to have begun with a 3in/30 (tentatively designated Mk XI) in October 1914. In addition to the 3in/50, there was interest in a 3in/35 (Mk XI). The 3in/50 was soon chosen. The prototype Mk X guns were completed by the Naval Gun Factory in 1914–15, and guns and mounts were tested in January 1916. BuOrd estimated that the lethal cone for the 3in/50 shrapnel round extended for 120 yds (10° cone); for a high-explosive shell it would extend about 25ft. These figures defined the allowable error in anti-aircraft fire.
The 3in/50 was the first US Navy gun designed specifically for anti-aircraft fire. Two turret-top 3in/50 anti-aircraft guns are visible on board the battleship Wyoming during a 10 March 1926 sub-calibre main battery firing exercise off Panama. Turret-top positions gave the best fields of fire, but the guns could not be used during a fleet action (due to blast) and ammunition supply was difficult. The same arguments applied fifteen years later when light anti-aircraft guns were mounted on ships’ turret tops.
A standard 3in/50 in service in the Second World War. So many such guns survived from First World War building programmes that production of new ones was not necessary until 1941. Some versions (Mods) of this Mk 11 had a platform for loaders raised well above the mount base, but that was not the case here. Mk 20 was the new-construction Second World War mounting, distinguishable by a prominent counterweight above the gun. It was an interim version using existing barrels. Mk 22 was all-new construction. Mk 21 was the corresponding wet mount for submarines, with a different gun designed to survive immersion.
The battleship New York shows her turret-top and crane-top 3in/50s in a photograph taken in the 1920s. She and the other older battleships retained their 3in guns when the newer battleships were refitted with 5in/25s. Although a director for these guns was to have been devised after the Mk 19 was fielded for the 5in/25, that never happened before the war, due to the lack of money. Even after a simple fire-control system appeared in the form of the Mk 51 and director, it offered no blind capability, leaving ships entirely exposed at night.
The original version of the 3in/50 anti-aircraft mount, Mk 11, from the 1945 Gun Mount and Turret Catalog. (Photograph by Richard S Pekelney, Historic Naval Ships Association, courtesy of Mr Pekelney)
The first battleships to have anti-aircraft guns incorporated in their designs were the 1915 class (Mississippi class), with four 3in/50. In December 1914 the Navy Department approved installation of four 3in/50 each on board the new Nevada and Pennsylvania class battleships due for completion in 1916. Texas had the prototype installation (1916). In 1917, when requirements were being drawn up for new battleships, the US Navy’s General Board proposed replacing these weapons with a new 4in anti-aircraft gun. BuOrd protested that a 4in gun would be too massive, and that its trunnions would be too high for efficient loading. The battery of the projected battleships was set at four 3in/50s. The standard four-gun battery was doubled to eight during the first round of post-war refits (1919–21), at the cost of two open-mount 5in/51 anti-destroyer guns.
During the war many battleships were armed with two such guns atop an after superfiring turret, but by 1917 much heavier batteries were wanted. The battleships designed in wartime were given batteries of eight 3in/50, typically on the deck above the secondary battery.
Lesser warships were also given anti-aircraft batteries. Characteristics for an abortive scout cruiser showed two anti-aircraft guns, and those for the Omaha class showed two heavy guns and two machine guns; the ships were completed with four 3in/50 each. The first destroyer whose Characteristics included an anti-aircraft gun was the Caldwell class (Destroyer 1916), but the earlier Sampsons were completed with two 1pdr pom-poms and a pair of 0.30-calibre machine guns. The wartime flush-deckers were to have had the same battery, but given the scarcity of pom-poms they received instead one 3in/23 and two (sometimes three) machine guns. The 3in/23 was typically mounted forward of the bridge. It had been hurriedly developed to replace existing 6pdrs aboard 110ft sub-chasers, its principal merit for anti-aircraft service being that it could fit in the same space as the pom-pom. Although it survived into the Second World War on board ‘flush deck’ destroyers (including those transferred to the United Kingdom in 1940), the 3in/23 was considered grossly inadequate even in 1917. It never seems to have been given any special means of fire control for it. By the end of the war, BuOrd was working on an entirely new 1pdr intended as the basis for a more powerful anti-aircraft weapon. It never entered service.20
A Second World War 3in/50 (Mk 20 or Mk 22) in action aboard an escort, probably a destroyer escort. Note the counterweight above the sights. Note also the pipe rack to prevent the gun from firing into the ship, an indication that it was not director-controlled (a director would incorporate stops to prevent such firing).
The standard Second World War version of the 3in/50 anti-aircraft gun. The smaller drawing shows the Mk 20 version, which used existing barrels. The externally indistinguishable Mk 22 had new barrels. (Photograph by Richard S Pekelney, Historic Naval Ships Association, courtesy of Mr Pekelney)
The Second World War Mk 22 used new-production barrels. Mk 26 was a power-driven version intended to work with the new 3in/50 Mk 50 director. (Photograph by Richard S Pekelney, Historic Naval Ships Association, courtesy of Mr Pekelney)
The US Navy adopted the 3in/23 (Mount Mk 14) for destroyers during the First World War, apparently because more suitable automatic weapons were in short supply. Given its low velocity, it was obsolescent during the First World War, but it survived aboard ‘flush-deckers’ into the next war. The 3in/23 also armed sub-chasers, and for that reason some were transferred to Italy during the First World War (the Italians also received, and retained, US Colt machine guns). This Mod