An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bullets) fired by a machine gun. Autocannons have a longer effective range and greater terminal performance than machine guns, due to the use of larger/heavier munitions, but are usually smaller than tank guns, howitzers, field guns or other artillery. When used on its own, the word "autocannon" typically indicates a non-rotary weapon with a single barrel. When multiple rotating barrels are involved, such a weapon is referred to as a "rotary autocannon" or occasionally "rotary cannon", for short.
The L and M class was a class of sixteen destroyers which served in the British Royal Navy during World War II. The ships of the class were launched between 1939 and 1942.
The 2-pounder gun, officially designated the QF 2-pounder and universally known as the pom-pom, was a 40-millimetre (1.6 in) British autocannon, used as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing. This QF 2-pounder was not the same gun as the Ordnance QF 2-pounder, used by the British Army as an anti-tank gun and a tank gun, although they both fired 2-pound (0.91 kg), 40-millimetre (1.6 in) projectiles.
The Type 96 25 mm gun was an automatic cannon used by the Imperial Japanese Navy during World War II. A locally-built variant of the French Hotchkiss 25 mm anti-aircraft gun, it was designed as a dual-purpose weapon for use against armored vehicles and aircraft, but was primarily used as an anti-aircraft gun in fixed mounts with one to three guns.
The Oerlikon 20 mm cannon is a series of autocannons, based on an original German Becker Type M2 20 mm cannon design that appeared very early in World War I. It was widely produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II. Many versions of the cannon are still used today.
The Flak 30 and improved Flak 38 were 20 mm anti-aircraft guns used by various German forces throughout World War II. It was not only the primary German light anti-aircraft gun but by far the most numerously produced German artillery piece throughout the war. It was produced in a variety of models, notably the Flakvierling 38 which combined four Flak 38 autocannons onto a single carriage.
The 3"/50 caliber gun in United States naval gun terminology indicates the gun fired a projectile 3 inches (76 mm) in diameter, and the barrel was 50 calibers long. Different guns of this caliber were used by the U.S. Navy and U.S. Coast Guard from 1890 through the 1990s on a variety of combatant and transport ship classes.
The 13.2 mm Hotchkiss machine gun model 1929, often simplified to Hotchkiss M1929 machine gun, and the like, was a heavy machine gun designed and manufactured by Hotchkiss et Cie from the late 1920s until World War II which saw service with various nations' forces, including Italy and Japan where the gun was built under license.
The QF 12-pounder 12-cwt gun was a common, versatile 3-inch (76.2 mm) calibre naval gun introduced in 1894 and used until the middle of the 20th century. It was produced by Armstrong Whitworth, Elswick and used on Royal Navy warships, exported to allied countries, and used for land service. In British service "12-pounder" was the rounded value of the projectile weight, and "12 cwt (hundredweight)" was the weight of the barrel and breech, to differentiate it from other "12-pounder" guns.
The Ordnance QF Hotchkiss 6 pounder gun Mk I and Mk II or QF 6 pounder 8 cwt were a family of long-lived light 57 mm naval guns introduced in 1885 to defend against new, small and fast vessels such as torpedo boats and later submarines. There were many variants produced, often under license which ranged in length from 40 to 58 calibers, but 40 caliber was the most common version.
The 4″/50 caliber gun was the standard low-angle, quick-firing gun for United States, first appearing on the monitor Arkansas and then used on "Flush Deck" destroyers through World War I and the 1920s. It was also the standard deck gun on S-class submarines, and was used to rearm numerous submarines built with 3-inch (76 mm) guns early in World War II. United States naval gun terminology indicates the gun fired a projectile 4 inches (100 mm) in diameter, and the barrel was 50 calibers long.
The 5"/25 caliber gun entered service as the standard heavy anti-aircraft (AA) gun for United States Washington Naval Treaty cruisers commissioned in the 1920s and 1930s. The goal of the 5"/25 design was to produce a heavy AA gun that was light enough to be rapidly trained manually. The gun was also mounted on pre-World War II battleships and aircraft carriers until replaced by the standard widespread dual-purpose 5"/38 caliber gun, which was derived from the 5"/25. Guns removed from battleships were probably converted for submarine use by late 1943, while a purpose-built variant for submarines was available in mid-1944, and was widely used by them. United States naval gun terminology indicates the gun fired a projectile 5 inches (127 mm) in diameter, and the barrel was 25 calibers long. It is referred to sometimes as a dual purpose gun and sometimes as an anti-aircraft gun, because of its comparative weakness against surface targets.
A deck gun is a type of naval artillery mounted on the deck of a submarine. Most submarine deck guns were open, with or without a shield; however, a few larger submarines placed these guns in a turret.
The QF 4.7 inch Gun Mark V originated as a 4.7 in (120 mm) 45-calibre naval gun designed by the Elswick Ordnance Company for export customers and known as the Pattern Y.
The Davis gun was the first true recoilless gun developed and taken into service. It was developed by Commander Cleland Davis of the US Navy, in 1910, just prior to World War I.
The 8.8 cm SK C/35 was a German naval gun used in World War II.
The 14 cm/50 3rd Year Type naval gun was a Japanese low-angle weapon introduced during World War I.
The Type 41 3-inch (76 mm) naval gun otherwise known as the 8 cm/40 3rd Year Type naval gun was a Japanese dual-purpose gun introduced before World War I. Although designated as 8 cm (3.15 in), its shells were 76.2 mm (3 in) in diameter.
The 12 cm 11th Year Type naval gun was a Japanese naval gun and coast defense gun used on submarines, minesweepers, and torpedo boats of the Imperial Japanese Navy during World War II.
The 12 cm/12 short naval gun was a naval gun used by the Imperial Japanese Navy to defend merchant ships and land bases during World War II.
Empire of Japan 
Imperial Japanese Navy 
