Rate of fire
Encyclopedia
Rate of fire is the frequency at which a specific weapon
can fire or launch its projectiles. It is usually measured in rounds per minute (RPM or round/min), or per second (RPS or round/s).
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.
For automatic weapons such as machine gun
s, the rate of fire is primarily a mechanical property.
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 past century, this increased firepower is due almost entirely to the higher rate of fire of modern weapons.
A good past example of growth in rate of fire would be the enormous advantage of the Maxim machine gun, which provided accurate and steady fire. This was due to technological advances in the field of material cooling
.
s have a cyclic rate of 500–900 RPM. Typical infantry machine gun
s have rates varying from 600 RPM to 1,200 RPM. M134
Miniguns mounted on helicopters can achieve rates of fire as high as 50 rounds per second (3,000 RPM).
. 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.
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 heavy machine gun, produced in both .30-06 Springfield
version and .50 BMG
versions: the former weighed 38 kg (84 lb), while the latter weighed 66 kg (121 lb) including coolant.http://www.navweaps.com/Weapons/WNUS_50cal-M2_MG.htm Due to these 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 miniguns can sustain fire far longer than ground-based counterparts, firing close to their cyclic rate of fire.
Another factor influencing rate of fire is the supply of ammunition. At 50 RPS, a five-second burst from the M134 would use approximately 2.5 kg (5.5 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.
Weapon
A weapon, arm, or armament is a tool or instrument used with the aim of causing damage or harm to living beings or artificial structures or systems...
can fire or launch its projectiles. It is usually measured in rounds per minute (RPM or round/min), or per second (RPS or round/s).
Overview
Note that both generation of heat (leading to weapon failure) and exhaustion of the weapon's ammunition mean that most automatic weapons are unlikely ever to sustain their cyclic rate of fire for a full minute; thus, it is technically incorrect and potentially misleading to describe RPM as "the number of rounds a weapon can fire in one minute."For manually operated weapons such as bolt-action
Bolt-action
Bolt action is a type of firearm action in which the weapon's bolt is operated manually by the opening and closing of the breech with a small handle, most commonly placed on the right-hand side of the weapon...
rifles or artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...
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
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...
or self-propelled gun
Self-propelled gun
A self-propelled gun is form of self-propelled artillery, and in modern use is usually used to refer to artillery pieces such as howitzers....
. 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.
For automatic weapons such as machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....
s, the rate of fire is primarily a mechanical property.
Over time, weapons have attained higher rates of fire. A small infantry
Infantry
Infantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of combat arms, they are the backbone of armies...
unit armed with modern assault rifles and machine guns can generate more firepower than much larger units equipped with older weapons. Over the past century, this increased firepower is due almost entirely to the higher rate of fire of modern weapons.
A good past example of growth in rate of fire would be the enormous advantage of the Maxim machine gun, which provided accurate and steady fire. This was due to technological advances in the field of material cooling
Engine cooling
Internal combustion engine cooling refers to the cooling of an internal combustion engine, typically using either air or a liquid.- Overview :...
.
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 squeezed, the rate at which rounds are fired is the cyclic rate. Typical assault rifleAssault rifle
An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...
s have a cyclic rate of 500–900 RPM. Typical infantry machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....
s have rates varying from 600 RPM to 1,200 RPM. M134
Minigun
The Minigun is a 7.62 mm, multi-barrel heavy machine gun with a high rate of fire , employing Gatling-style rotating barrels with an external power source...
Miniguns mounted on helicopters can achieve rates of fire as high as 50 rounds per second (3,000 RPM).
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 to know 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 rpm, except for barrel changes it considers most of the same factors as for the belt fed MGs.Rapid rate
Rapid rate is a rate of fire between Cyclic and Sustained. It usually uses longer bursts 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 significant amount of ammunition (more than the gunner or assistant gunner are likely to carry on a patrol), the heat generated requires barrel change times to be reduced, and because machine guns are only issued with one spare barrel prolonged rapid fire will result in shortened weapon/barrel life.Semi-Automatic rate
The semi-automatic rate is the assault rifle/semi-auto only version on rapid fire. It is the maximum rate that a weapon can fire with any degree of accuracy in semi-auto mode, usually 45-60 rpm.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 overheatingOverheating
Overheating may refer to:*Hyperthermia, also called sunstroke, an elevated body temperature due to failed thermoregulation*Thermal shock, the overheating of a device leading to reduced efficiency, damage or even destruction...
. 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
Cooking off
Cooking off refers to ammunition exploding prematurely due to heat in the surrounding environment. It can also refer to a technique used when throwing grenades to achieve a controlled, predictable explosion....
), or, what is much worse in combat, failure to fire.
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 heavy machine gun, produced in both .30-06 Springfield
.30-06 Springfield
The .30-06 Springfield cartridge or 7.62×63mm in metric notation, was introduced to the United States Army in 1906 and standardized, and was in use until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy, and .30 US Army...
version and .50 BMG
.50 BMG
The .50 Browning Machine Gun or 12.7×99mm NATO is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge...
versions: the former weighed 38 kg (84 lb), while the latter weighed 66 kg (121 lb) including coolant.http://www.navweaps.com/Weapons/WNUS_50cal-M2_MG.htm Due to these disadvantages, water-cooled weapons have gradually been replaced by much lighter air-cooled weapons. For weapons mounted on aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
, 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 miniguns can sustain fire far longer than ground-based counterparts, firing close to their cyclic rate of fire.
Another factor influencing rate of fire is the supply of ammunition. At 50 RPS, a five-second burst from the M134 would use approximately 2.5 kg (5.5 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.