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Tracer ammunition (AMO) (Tracers) are
bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and ...
s or
cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder duri ...
-caliber
projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found i ...
s that are built with a small
pyrotechnic Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarrying, and demolition ...
charge in their base. When fired, the pyrotechnic composition is ignited by the burning powder and burns very brightly, making the projectile trajectory visible to the naked eye during daylight, and very bright during nighttime firing. This allows the shooter to visually trace the flight path of the projectile and thus make necessary ballistic corrections, without having to confirm projectile impacts and without even using the
sights A sight is an aiming device used to assist in visually aligning ranged weapons, surveying instruments or optical illumination equipments with the intended target. Sights can be a simple set or system of physical markers that have to be aligne ...
of the weapon. Tracer fire can also be used as a marking tool to signal other shooters to concentrate their fire on a particular target during battle. When used, tracers are usually loaded as every fifth
round Round or rounds may refer to: Mathematics and science * The contour of a closed curve or surface with no sharp corners, such as an ellipse, circle, rounded rectangle, cant, or sphere * Rounding, the shortening of a number to reduce the numbe ...
in machine gun belts, referred to as four-to-one tracer.
Platoon A platoon is a military unit typically composed of two or more squads, sections, or patrol A patrol is commonly a group of personnel, such as Law enforcement officer, law enforcement officers, military personnel, or Security guard, secur ...
and squad leaders will load some tracer rounds in their magazine or even use solely tracers to mark targets for their soldiers to fire on. Tracers are also sometimes placed two or three rounds from the bottom of magazines to alert shooters that their weapons are almost empty. During
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
,
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It 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. ...
with fixed machine guns or
cannons A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder during ...
mounted would sometimes have a series of tracer rounds added near the end of the ammunition belts, to alert the pilot that he was almost out of ammunition. However, this practice similarly alerted astute enemies that their foes were nearly out of ammunition. More often, however, the entire magazine was loaded four-to-one, on both fixed offensive and flexible defensive guns, to help mitigate the difficulties of aerial gunnery. Tracers were very common on most WWII aircraft, with the exception of
night fighter A night fighter (also known as all-weather fighter or all-weather interceptor for a period of time after the Second World War) is a fighter aircraft adapted for use at night or in other times of bad visibility. Night fighters began to be used ...
s, which needed to be able to attack and shoot down the enemy before they realized they were under attack, and without betraying their own location to the enemy defensive gunners. The United States relied heavily on tracer ammunition for the defensive
Browning M2 The M2 machine gun or Browning .50 caliber machine gun (informally, "Ma Deuce") is a heavy machine gun that was designed towards the end of World War I by John Browning. Its design is similar to Browning's earlier M1919 Browning machine gun, ...
.50 caliber This is a list of firearm cartridges which have bullets in the to caliber range. *''Length'' refers to the cartridge case Case or CASE may refer to: Containers * Case (goods), a package of related merchandise * Cartridge case or casing, a ...
machine guns on its heavy bombers such as the
B-24 Liberator The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models d ...
.


History

There are fireworks manuals from the 14th century specifying a way to make "flaming cannonballs," with pitch, gunpowder, a cloth/cordage cover, and finally smearing them with lard and tallow. These were however not available for small arms, and before the development of tracers, gunners still relied on seeing their bullets impact to adjust their aim. However, these were not always visible, especially as the effective range of ammunition increased dramatically during the later half of the 19th century, meaning the bullets could impact a mile or more away in long range area fire. In the early 20th century, ammunition designers developed " spotlight" bullets, which would create a flash or smoke puff on impact to increase their visibility. However, these projectiles were deemed in violation of the Hague Conventions prohibition of "exploding bullets." This strategy was also useless when firing at aircraft, as there was nothing for the projectiles to hit if they missed the target. Designers also developed bullets that would trail white
smoke Smoke is a suspension of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrainment (engineering), entrained or otherwise mixed into the mass. It is commo ...
. However, these designs required an excessive amount of
mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different element ...
loss to generate a satisfactory trail. The loss of mass en route to the target severely affected the bullet's
ballistics Ballistics is the field of mechanics concerned with the launching, flight behaviour and impact effects of projectiles, especially ranged weapon munitions such as bullets, unguided bombs, rockets or the like; the science or art of designing ...
. The
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
was the first to develop and introduce a tracer round, a version of the .303 cartridge in 1915. The
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
introduced a .30-06 tracer in 1917. Prior to adopting red (among a variety of other colors) bullet tips for tracers, American tracers were identified by blackened cartridge cases. Tracers proved useful as a
countermeasure A countermeasure is a measure or action taken to counter or offset another one. As a general concept, it implies precision and is any technological or tactical solution or system designed to prevent an undesirable outcome in the process. The fi ...
against
Zeppelin A Zeppelin is a type of rigid airship named after the German inventor Count Ferdinand von Zeppelin () who pioneered rigid airship development at the beginning of the 20th century. Zeppelin's notions were first formulated in 1874Eckener 1938, ...
s used by
Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...
during
World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...
. The
airship An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air. In early ...
s were used for
reconnaissance In military operations, reconnaissance or scouting is the exploration of an area by military forces to obtain information about enemy forces, terrain, and other activities. Examples of reconnaissance include patrolling by troops ( skirmishe ...
, surveillance and bombing operations. Normal bullets merely had the effect of causing a slow leak, but tracers could ignite the
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
gasbags, and bring down the airship quickly. In World War II US naval and marine aircrew were issued tracer rounds with their side arms for emergency signaling use as well as defense.


Construction

A tracer projectile is constructed with a hollow base filled with a pyrotechnic flare material, made of a mixture of a very finely ground metallic fuel,
oxidizer An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...
, and a small amount of organic fuel. Metallic fuels include
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
,
aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It h ...
, and occasionally
zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'' ...
. The oxidizer is a salt molecule which contains oxygen combined with a specific atom responsible for the desired color output. Upon ignition, the heated salt releases its oxygen to sustain combustion of the fuel in the mixture. The color-emitting atom in the salt is also released and reacts chemically with excess oxygen providing the source of the colored flame. In
NATO The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...
standard ammunition (including US), the oxidizer salt is usually a mixture of
strontium Strontium is the chemical element with the symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is ...
compounds (
nitrate Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble ...
,
peroxide In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen ...
, etc.) and the metallic fuel is magnesium. Burning strontium yields a bright red light.
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eigh ...
n and Chinese tracer ammunition generates green light using
barium Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. ...
salts. An oxidizer and metallic fuel alone, however, do not make a practical pyrotechnic for the purposes of producing colored light. The reaction is too energetic, consuming all materials in one big flash of white lightwhite light being the characteristic output of magnesium-oxide (MgO), for example. Therefore, in the case of using strontium nitrate and magnesium, to produce a red colored flame that is not over-powered by the white light from the burning fuel, a
chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is ...
donor is provided in the pyrotechnic mixture, so that strontium chloride can also form in the flame, cooling it so that the white light of MgO is greatly reduced. Cooling the flame in this manner also lengthens the reaction rate so that the mixture has an appreciable burn time. Polyvinyl chloride (PVC) is a typical organic fuel in colored light for this purpose. Some modern designs use compositions that produce little to no
visible light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...
and radiate mainly in
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from aroun ...
, being visible only on
night vision Night vision is the ability to see in low-light conditions, either naturally with scotopic vision or through a night-vision device. Night vision requires both sufficient spectral range and sufficient intensity range. Humans have poor night ...
equipment.


Types

There are three types of tracers: bright tracer, subdued tracer and dim tracer. Bright tracers are the standard type, which start burning very shortly after exiting the muzzle. A disadvantage of bright tracers is that they give away the shooter's location to the enemy; as a military adage puts it, "tracers work both ways". Bright tracers can also overwhelm night-vision devices, rendering them useless. Subdued tracers burn at full brightness after a hundred or more yards to avoid giving away the gunner's position. Dim tracers burn very dimly but are clearly visible through night-vision equipment. The M196 tracer cartridge (54-
grain A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legu ...
bullet)
5.56×45mm NATO The 5.56×45mm NATO (official NATO nomenclature 5.56 NATO, but often pronounced "five-five-six") is a rimless bottlenecked intermediate cartridge family developed in the late 1970s in Belgium by FN Herstal. It consists of the SS109, L110, and ...
was developed for the original M16 rifle and is compatible with the M16A1 barrel also using 1:12 rifling twist. It has a red tip and is designed to trace out to 500 yards, and trajectory match the M193 (56-grain) ball cartridge, which has no tip color. Trajectory match, or ballistic match, is achieved between two bullets of slightly different weight and aerodynamic characteristics by adjusting the cartridge propellant weight, propellant type, and muzzle velocity, to remain within safe pressure limits, yet provide each bullet with a trajectory to the target that is nearly identical over all atmospheric conditions and target engagement ranges, while using the same gunsight aimpoint. Trajectory match is not intended to be perfect, an engineering impossibility under the closest of similarities between the two bullets, that is further complicated in the case of the tracer losing mass and changing its drag properties as it flies. The intent is that the tracer matches the ball round well enough for the purposes of machinegun fire. The M856 tracer cartridge (63.7-grain bullet) is used in the M16A2/3/4, M4-series, and M249 weapons (among other 5.56mm NATO weapons). This round is designed to trace out to 875 yards and has an orange tip color, and is trajectory matched to the M855 (62-grain, green tip) ball cartridge. The M856 tracer should not be used in the M16A1 except under emergency conditions and only in relatively warm weather, because the M16A1's slower 1:12 rifling twist is not sufficient to properly stabilize this projectile at colder combat service temperatures (freezing down to –40 degrees), when the air density is much greater, disrupting the gyroscopic stability of the bullet. The M16A2 and newer models have a rifling twist of 1 in 7" necessary to stabilize the M856 tracer round under all temperature conditions. (The M196, however, does function safely in all 1:7 twist barrels, as well as those with 1:12 twist.) The M25 is an orange-tipped .
30-06 The .30-06 Springfield cartridge (pronounced "thirty- aught-six" ), 7.62×63mm in metric notation, and called the .30 Gov't '06 by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in military use ...
Springfield tracer cartridge consisting of a 145 gr bullet with 50 grains of IMR 4895 powder. The tracer compound contains composition R 321 which is 16% polyvinyl chloride, 26%
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
powder, 52% strontium nitrate. The M62 is an orange-tipped
7.62×51mm NATO The 7.62×51mm NATO (official NATO nomenclature 7.62 NATO) is a rimless, bottlenecked rifle cartridge. It is a standard for small arms among NATO countries. First developed in the 1950s, the cartridge had first been introduced in U.S. service fo ...
tracer consisting of a 142 gr bullet with 46 grains of WC 846 powder. The tracer compound contains composition R 284 which is 17% polyvinyl chloride, 28% magnesium powder, and 55% strontium nitrate. (This is the same composition used on the M196. The M276 is a violet-tipped 7.62×51mm NATO dim tracer that uses composition R 440, which is
barium peroxide Barium peroxide is the inorganic compound with the formula Ba O2. This white solid (gray when impure) is one of the most common inorganic peroxides, and it was the first peroxide compound discovered. Being an oxidizer and giving a vivid green ...
, strontium peroxide, calcium resinate for example calcium abietate, and
magnesium carbonate Magnesium carbonate, (archaic name magnesia alba), is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals. Forms The most common magnesium carbonate forms are ...
. Tracer compositions can also emit primarily in
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from aroun ...
, for use with night-vision devices. An example composition is boron,
potassium perchlorate Potassium perchlorate is the inorganic salt with the chemical formula K Cl O4. Like other perchlorates, this salt is a strong oxidizer although it usually reacts very slowly with organic substances. This, usually obtained as a colorless, crys ...
, sodium salicylate, iron carbonate or
magnesium carbonate Magnesium carbonate, (archaic name magnesia alba), is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals. Forms The most common magnesium carbonate forms are ...
(as combustion retardant), and binder. Many variants exist.


Other applications

Tracers can also serve to direct fire at a given target, because they are visible to other combatants. The disadvantage is that they betray the gunner's position; the tracer path leads back to its source. To make it more difficult for an enemy to do this, most modern tracers have a delay element, which results in the trace becoming visible some distance from the muzzle. Depending on the target, tracer bullet lethality may be similar to standard ball ammunition. The forward portion of a tracer bullet contains a substantial slug of lead filler, nearly as much as the non-tracer ball round that it trajectory matches. In the case of the M196/M193 bullet set, the lethality differences are probably negligible for this reason. However, with the M856/M855 bullet set, the M855 ball round contains a steel penetrator tip that is not present in the M856 tracer bullet. As a result, different lethality effects can be expected against various targets. Nevertheless, under some circumstances, a slight degradation in lethality can often be made up for by the psychological and suppressive-fire effects tracer bullets can have on an enemy who is receiving them. Besides guiding the shooter's direction of fire, tracer rounds can also be loaded at the end of a magazine to alert the shooter that the magazine is almost empty. This is particularly useful in weapons that do not lock the bolt back when empty (such as the
AK-47 The AK-47, officially known as the ''Avtomat Kalashnikova'' (; also known as the Kalashnikov or just AK), is a gas-operated assault rifle that is chambered for the 7.62×39mm cartridge. Developed in the Soviet Union by Russian small-arms des ...
). During
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, the
Soviet Air Force The Soviet Air Forces ( rus, Военно-воздушные силы, r=Voyenno-vozdushnyye sily, VVS; literally "Military Air Forces") were one of the air forces of the Soviet Union. The other was the Soviet Air Defence Forces. The Air Forces ...
also used this practice for aircraft machine guns. One disadvantage in this practice is that the enemy is alerted that the pilot or shooter is low on ammunition and possibly vulnerable. For ground forces, this generally offers no tactical advantage to the enemy, since a soldier with a crew-served weapon such as a machine gun who is out of ammunition is supposed to alert his team that he is "dry" and rely on their
cover fire In military science, suppressive fire is "fire that degrades the performance of an enemy force below the level needed to fulfill its mission". When used to protect exposed friendly troops advancing on the battlefield, it is commonly called cove ...
while he reloads the machine gun. Thus, an enemy must risk exposing himself in order to attack the reloading soldier. Modern jet fighters primarily rely on
radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
and infrared seeker
missile In military terminology, a missile is a missile guidance, guided airborne ranged weapon capable of self-propelled flight usually by a jet engine or rocket motor. Missiles are thus also called guided missiles or guided rockets (when a previously ...
s to track and destroy enemy planes and
laser-guided Laser guidance directs a robotics system to a target position by means of a laser beam. The laser guidance of a robot is accomplished by projecting a laser light, image processing and communication to improve the accuracy of guidance. The key ide ...
missiles to attack surface targets, rather than the plane's
cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder duri ...
, which may be just an ancillary weapon for air-to-air combat; although in the ground attack role, cannon fire may be emphasized. However, modern fighter aircraft use gyroscopes and inertial sensors coupled with radar and optical computing gunsights that make the use of tracers in cannon ammunition unnecessary. As long as the pilot can put the "pipper" (aiming point) in the head-up display (HUD) onto the target, he can be assured that the burst will be on target, since the computers automatically compute range, closing rate, deflection, lateral accelerations, and even weather conditions to calculate target lead and aimpoint. Thus one of the primary reasons for using tracers on aircraft in the first place, uncertainty over where the bullets will end up in relation to the target, is removed. Another use for the tracer is in tank hull machineguns, of mostly out-dated tanks, where the machinegun operator cannot sight directly along the barrel, thus he has to rely on tracer bullets to guide his aim. Modern main battle tanks and armored fighting vehicles, however, employ advanced fire control systems that can accurately aim secondary weapons along with the main armament; although the continued use of tracers provides reassurance to gunners on the direction of machinegun fire.


Safety restrictions

In the UK, use of tracer rounds are restricted on
National Rifle Association The National Rifle Association of America (NRA) is a gun rights advocacy group based in the United States. Founded in 1871 to advance rifle marksmanship, the modern NRA has become a prominent gun rights lobbying organization while cont ...
-operated ranges, due to an increased risk of fire. Unauthorized use is punished at the discretion of the acting range officer. Use of tracers is usually only authorized during military training. In July 2009, a large fire was started by tracer ammunition near
Marseille Marseille ( , , ; also spelled in English as Marseilles; oc, Marselha ) is the prefecture of the French department of Bouches-du-Rhône and capital of the Provence-Alpes-Côte d'Azur region. Situated in the camargue region of southern Fran ...
,
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...
, an area where shrub vegetation is very dry and flammable in the summer, and where normally this kind of ammunition should not be used. On February 24, 2013, a fire was started at DFW Gun Club in Dallas, Texas by the use of a tracer round inside the facility. On July 3, 2018, the Lake Christine Fire near Basalt, Colorado was started by tracer rounds fired at a gun range. The two individuals who were deemed responsible for the fire were shooting the tracer round ammunition outside of the designated target area at the gun range.


See also

*
Fire arrow Fire arrows were one of the earliest forms of weaponized gunpowder, being used from the 9th century onward. Not to be confused with earlier incendiary arrow projectiles, the fire arrow was a gunpowder weapon which receives its name from the tra ...
*
Incendiary ammunition Incendiary ammunition is a type of ammunition that contains a chemical that, upon hitting a hard obstacle, has the characteristic of causing fire/setting flammable materials in the vincinity of the impact on fire. World War I The first time ince ...
* Variable density goggles


References


External links


2010 article with photographs of tracers at night



M25 and M62
(.30 caliber) tracer bullet analysis {{DEFAULTSORT:Tracer Ammunition Projectiles Pyrotechnics