Britannia’s version of the ‘quad 50’
While the U.S. Army’s M45 Maxson “Meatchopper” four-pack of air-cooled M2 .50-cal BMG (12.7x99mm) heavy machine guns is legendary, Britain’s version, used almost exclusively for shipborne anti-aircraft artillery, gets considerably less attention.
The Vickers 0.5-inch was an altogether different gun and caliber (12.7x81mm) with 690-grain Semi-Armour Piercing (SAP) and 664-grain Semi-Armour Piercing-Tracer (SAPT) rounds favored in RN use. The round, according to some bullet collectors, was invented by necking down a .600 Nitro Express.
While the Army and RAF used the same gun, typically in single mounts, the cyclic rate was pretty slow (400 rpms). The RN’s version lacked the delay pawl and used heavier springs, almost doubling that rate of fire.
Classified as the Vickers Mark III No. 1, the mount weighed in at 2,580 pounds when fully loaded and included a quartet of water-cooled .50 cals, capable of depressing/elevating -10 / +80 degrees. Unlike the Maxson which was electrically powered via a small gasoline engine, the Vickers relied on a pair of Jack Tars working their elevation and azimuth wheels while sometimes a third rating served as the mount’s captain/spotter.
The guns could be calibrated to have a spread of fire 60 feet wide and 50 feet high at 1,000 yards, which is a pretty effective cone, though a short-ranged one.
Each machine gun had a 200-round belt in a drum can, giving the gun 800 rounds at the ready. As cyclic rate per gun could run as fast as 700rpms, you could drain a mount’s onboard ammo supply in well under a minute of constant firing. However, as you are dealing with a water-cooled machine gun (each held 3.5 quarts in its jacket), simply add another belt and get back into the fight. A new belt could be added to a gun in 16 seconds or less, with two gunners recharging all four guns within a minute.
According to Navweaps, production started on these guns as early as 1926 and they were no doubt effective against the biplanes of that day. However, as planes got faster and heavier, the prospect of using .50 cal– even massed– had rather expired in the early days of WWII. Indeed, by the end of that conflict, the U.S. Navy was distancing not only 20mm Oerlikons but also 40mm Bofors in favor of rapid-fire radar directed 3″ and 5″ DP mounts.
Apparently, some 12,500 of these guns (in several varieties not limited to the quad mount shown here) were produced and a limited number were exported to Japan and China before 1939.
These guns, nonetheless, were very common on British and Commonwealth ships as well as Soviet vessels passed on, being mounted on everything from converted trawlers to aircraft carriers (HMS Ark Royal had eight such quad mounts in 1940).
These guns no doubt lingered in service with third-world navies on surplus RN ships through the 1960s or later.