Rate of fire

Last updated

Rate of fire is the frequency at which a specific weapon can fire or launch its projectiles. This can be influenced by several factors, including operator training level, mechanical limitations, ammunition availability, and weapon condition. In modern weaponry, it is usually measured in rounds per minute (RPM or round/min) or rounds per second (RPS or round/s).


There are three different measurements for the rate of fire: cyclic, sustained, and rapid. Cyclic is the maximum rate of fire given only mechanical function, not taking into account degradation of function due to heat, wear, or ammunition constraints. Sustained is the maximum efficient rate of fire given the time taken to load the weapon and keep it cool enough to operate. Finally, rapid is the maximum reasonable rate of fire in an emergency situation when the rate of fire need not be upheld for long periods.


For manually operated weapons such as bolt-action rifles or artillery pieces, the rate of fire is governed primarily by the training of the operator or crew, within some mechanical limitations. Rate of fire may also be affected by ergonomic factors. For rifles, ease-of-use features such as the design of the bolt or magazine release can affect the rate of fire.

For artillery pieces, a gun on a towed mount can usually achieve a higher rate of fire than the same weapon mounted within the cramped confines of a tank or self-propelled gun. This is because the crew operating in the open can move more freely and can stack ammunition where it is most convenient. Inside a vehicle, ammunition storage may not be optimized for fast handling due to other design constraints, and crew movement may be constricted. Artillery rates of fire were increased in the late 19th century by innovations including breech-loading and quick-firing guns.

For automatic weapons such as machine guns, the rate of fire is primarily a mechanical property. A high cyclic firing rate is advantageous for use against targets that are exposed to a machine gun for a limited time span, like aircraft or targets that minimize their exposure time by quickly moving from cover to cover. For targets that can be fired on by a machine gun for longer periods than just a few seconds the cyclic firing rate becomes less important.

For a third hybrid class of weapons, common in handguns and rifles, known as a semi-automatic firearm, the rate of fire is primarily governed by the ability of the operator to actively pull the trigger. No other factors significantly contribute to the rate of fire. Generally, a semi-automatic firearm automatically chambers a round using blowback energy, but does not fire the new round until the trigger is released to a reset point and actively pulled again. Semi-automatics' rate of fire is significantly different from and should not be confused with full-automatics' rate of fire. Many full-automatic small arms have a selective fire feature that 'downgrades' them to semi-automatic mode by changing a switch.

Over time, weapons have attained higher rates of fire. A small infantry unit armed with modern assault rifles and machine guns can generate more firepower than much larger units equipped with older weapons. Over the 20th century, this increased firepower was due almost entirely to the higher rate of fire of modern weapons.

A good example of growth in rate of fire is the Maxim machine gun that was developed in 1884 and used until World War I ended in 1918. Its performance was improved during that time mainly by advances in the field of cooling.


There are diverse measurements of rate of fire. The speed of the fire will vary depending on the type of automatic weapon.

Cyclic rate

This is the mechanical rate of fire, or how fast the weapon "cycles" (loads, locks, fires, unlocks, ejects). Measurement of the cyclic rate assumes that the weapon is being operated as fast as possible and does not consider operator tasks (magazine changes, aiming, etc.). When the trigger is pulled, the rate at which rounds are fired is the cyclic rate. Typical cyclic rates of fire are 600–900 RPM for assault rifles, 1,000-1,100 RPM in some cases, 900-1,200 RPM for submachine guns and machine pistols, and 600-1,500 RPM for machine guns. M134 Miniguns mounted on attack helicopters and other combat vehicles can achieve rates of fire of over 100 rounds per second (6,000 RPM). Cyclic rate of fire is the only rate that can be determined precisely.

Sustained or effective rate

This is the rate at which the weapon could reasonably be fired indefinitely without failing. In contrast to the cyclic rate, the sustained rate is the actual rate at which the weapon would typically be fired in combat. Sustained rate considers several factors, time spent reloading, aiming, changing barrels if necessary, and allowing for some cooling. Knowing the sustained rate of fire is useful for logistics and supply purposes. Machine guns are typically fired in short bursts rather than in long continuous streams of fire, although there are times when they must be fired in very long bursts (see rapid rate below). Sustained rate also applies to box magazine fed assault rifles and semi-automatic rifles. In these weapons it refers to the rate at which the typical rifleman can effectively engage targets in a combat situation. The rate is usually 12-15 rounds per minute; except for barrel changes it considers most of the same factors as for the belt fed machine guns.

Rapid rate

Rapid rate is a rate of fire between cyclic and sustained. It is usually much faster, although less accurate, than the sustained rate and is only used in emergency/final defensive line situations. The rapid rate is not sustainable for long periods because it eats up a great amount of ammunition (more than the troops are likely to carry on a patrol), the heat generated requires barrel change times to be reduced, and with the one spare barrel usually issued, prolonged rapid fire will result in shortened weapon/barrel life.

Technical limitations

The major limitation in higher rates of fire arises due to the problem of heat. Even a manually operated rifle generates heat as rounds are fired. A machine gun builds up heat so rapidly that steps must be taken to prevent overheating. Solutions include making barrels heavier so that they heat up more slowly, making barrels rapidly replaceable by the crews, or using water jackets around the barrel to cool the weapon. A modern machine gun team will carry at least one spare barrel for their weapon, which can be swapped out within a few seconds by a trained crew. Problems with overheating can range from ammunition firing unintentionally (cook-off), or, what is much worse in combat, failure to fire or explosion of the weapon.

Water-cooled weapons can achieve very high effective rates of fire (approaching their cyclic rate) but are very heavy and vulnerable to damage. A well-known example is the M1917 Browning machine gun, a heavy machine gun designed by John Browning and used by US forces during WWI. It became the basis of the much more common Browning M1919 machine gun, used by US forces throughout World War II, as well as the Browning M2 .50 caliber heavy machine gun, which is still in service, as well as many adaptions, such as the Japanese Ho-103 aircraft machine gun during World War II. [1] Another legendarily reliable heavy machine gun is the British Vickers machine gun, based on the Maxim machine gun design, which saw service both on the air and ground during World War I and World War II. Due to their disadvantages, water-cooled weapons have gradually been replaced by much lighter air-cooled weapons. For weapons mounted on aircraft, no cooling device is necessary due to the outside air cooling the weapon as the aircraft is moving. Consequently, aircraft-mounted machine guns, autocannon or Gatling-type guns can sustain fire far longer than ground-based counterparts, firing close to their cyclic rate of fire. However, due to the weight of the ammunition, sustained fire is constrained by ammunition payload, as many aircraft cannons only carry enough ammunition for a few seconds' worth of firing; for example, the F-16 Falcon and its variants carry 511 rounds of 20mm ammunition, and the F-22 Raptor carries a similar amount at 480 rounds, which equates to roughly 5 seconds of firing at the M61 Vulcan's 6000rpm (100 rounds per second) cyclic rate. Some aircraft, due to the purpose of the design, do carry more, such as the GAU-8 mounted on the A-10 Thunderbolt, which carries 1,150 rounds of ammunition sufficient for 17 seconds of firing).

Another factor influencing rate of fire is the supply of ammunition. At 50 RPS (3,000 RPM), a five-second burst from an M134 Minigun would use approximately 6.3 kilograms (14 lb) of 7.62 mm ammunition; this alone would make it an impractical weapon for infantry who have to carry a reasonable supply of ammunition with them. For this and other reasons, weapons with such high rates of fire are typically only found on vehicles or fixed emplacements.

See also

Related Research Articles

Machine gun Sustained fully-automatic firearm

A machine gun is an auto-firing, rifled long-barrel autoloading firearm designed for sustained direct fire with fully powered cartridges. Other automatic firearms such as assault rifles and automatic rifles are typically designed more for firing short bursts rather than continuous firepower, and not considered machine guns. Squad automatic weapons, which fire the same cartridge used by the other riflemen from the same combat unit, are functionally light machine guns though not called so. Submachine guns, which are capable of continuous rapid fire but using handgun cartridges, are also not technically regarded as true machine guns.

A rifle is a long-barrelled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves (rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with both hands and braced firmly against the shooter's shoulder via a buttstock for stability during shooting. Rifles are used extensively in warfare, self defense, law enforcement, hunting, and shooting sports.

The MG 34 is a German recoil-operated air-cooled machine gun, first tested in 1929, introduced in 1934, and issued to units in 1936. It introduced an entirely new concept in automatic firepower – the Einheitsmaschinengewehr – and is generally considered the world's first general-purpose machine gun (GPMG). Both the MG 34 and MG 42 were erroneously nicknamed "Spandau" by Allied troops, a carryover from the World War I nickname for the MG 08, which was produced at the Spandau Arsenal.

The MG 42 is a 7.92×57mm Mauser general-purpose machine gun designed in Nazi Germany and used extensively by the Wehrmacht and the Waffen-SS during the second half of World War II. Entering production in 1942, it was intended to supplement and replace the earlier MG 34, which was more expensive and took much longer to produce, but both weapons were produced until the end of World War II.

M2 Browning Type of heavy machine gun

The M2 machine gun or Browning .50 caliber machine gun is a heavy machine gun designed toward the end of World War I by John Browning. Its design is similar to Browning's earlier M1919 Browning machine gun, which was chambered for the .30-06 cartridge. The M2 uses the much larger and much more powerful .50 BMG cartridge, which was developed alongside and takes its name from the gun itself. It has been referred to as "Ma Deuce", in reference to its M2 nomenclature. The design has had many specific designations; the official US military designation for the current infantry type is Browning Machine Gun, Cal. .50, M2, HB, Flexible. It is effective against infantry, unarmored or lightly armored vehicles and boats, light fortifications, and low-flying aircraft.


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 simply "rotary cannon".

The M60, officially the Machine Gun, Caliber 7.62 mm, M60, is a family of American general-purpose machine guns firing 7.62×51mm NATO cartridges from a disintegrating belt of M13 links. There are several types of ammunition approved for use in the M60, including ball, tracer, and armor-piercing rounds.

Cooking off is ammunition exploding prematurely due to heat in the surrounding environment.

M240 machine gun Family of machine guns

The M240, officially the Machine Gun, 7.62 mm, M240, is the U.S. military designation for the FN MAG, a family of belt-fed, gas-operated medium machine guns that chamber the 7.62×51mm NATO cartridge.

Vickers machine gun Medium machine gun

The Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled .303 British (7.7 mm) machine gun produced by Vickers Limited, originally for the British Army. The machine gun typically required a six- to eight-man team to operate: one fired, one fed the ammunition, the rest helped to carry the weapon, its ammunition, and spare parts. Not to be confused with the Maxim machine gun, it was in service from before the First World War until the 1960s, with air-cooled versions of it on many Allied World War I fighter aircraft.

Automatic firearm firearm that will continue to fire so long as the trigger is pressed and held

An automatic firearm is a firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discharge to feed a new ammunition round into the chamber, and then ignite the propellant and discharge the projectile by delivering a hammer/striker impact on the primer.

Stoner 63 Modular weapon system *Rifle *Carbine *Assault rifle *Light machine gun *Squad automatic weapon

The Stoner 63 is a 5.56×45mm NATO modular weapon system. Using a variety of modular components, it can be configured as a rifle, a carbine, a top-fed light machine gun, a belt-fed squad automatic weapon, or a vehicle mounted weapon. Also known as the M63, XM22, XM23, XM207 or the Mk 23 Mod 0 machine gun, it was designed by Eugene Stoner in the early 1960s. Cadillac Gage was the primary manufacturer of the Stoner 63 during its history. The Stoner 63 saw very limited combat use by United States forces during the Vietnam War. A few were also sold to law enforcement agencies.

Rotary cannon

A rotary cannon, rotary autocannon, rotary gun or Gatling cannon, is any large-caliber multiple-barreled automatic firearm that uses in a Gatling-type rotating barrel assembly to deliver a sustained saturational direct fire at much greater rates of fire than single-barreled autocannons of the same caliber. The loading, firing and ejection functions are performed simultaneously in different barrels as the whole assembly rotates, and the rotation also permits the barrels some time to cool. The rotating barrels on nearly all modern Gatling-type guns are powered by an external force such as an electric motor, although internally powered gas-operated versions have also been developed.

Heavy machine gun Machine gun capable of relatively heavy sustained fire

A heavy machine gun or HMG is a belt-fed machine gun that fires full-powered/magnum cartridges and is designed to be significantly more massive than light, medium or general-purpose machine guns. As the name implies, heavy machine guns are typically not man-portable by infantry and thus require mounting onto a weapons platform to be operably stable or tactically mobile, have more formidable firepower, and generally require a team of personnel for operation and maintenance.

Oerlikon 20 mm cannon Autocannon

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, and many versions are still in use today.

XM214 Microgun An American prototype 5.56 mm rotary-barreled machine gun

The XM214 Microgun is an American prototype 5.56 mm rotary-barreled machine gun. It was designed and built by General Electric. The XM214 was a scaled-down smaller and lighter version of the M134 Minigun, firing M193 5.56×45mm ammunition.

Medium machine gun

A medium machine gun (MMG), in modern terms, usually refers to a belt-fed machine gun firing a full-powered rifle cartridge, and is considered "medium" in weight. Medium machine guns are light enough to be infantry-portable, but still cumbersome enough to require a crew for optimal operational efficiency.

2 cm Flak 30, Flak 38 and Flakvierling 38 Anti-aircraft weaponAnti-materiel and anti-personnel weapon

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.

Reibel machine gun Machine gun

The MAC mle 1931 machine gun, was a machine gun used in French tanks of the World War II era, as well as in fortifications such as the Maginot line. It is also sometimes known as the JM Reibel, from Jumelage de mitrailleuses, or Reibel twin-mounted guns and really refers to the specialized twin-mounting frame used in JM cloche cupolas on the Maginot Line fortifications, while MAC mle 1931 refers specifically to the gun. The JM twin-mounts were the standard emplacement for the mle 1931 in fixed fortifications, while tanks and other AFVs received single guns.

The Ameli is a 5.56mm light machine gun designed for the Spanish Army by the nationally owned and operated Centro de Estudios Técnicos de Materiales Especiales (CETME) small arms research institute.


  1. "United States of America 0.50"/90 (12.7 mm) M2 Browning MG" . Retrieved December 19, 2012.