Shell (projectile)
Overview
 
A shell is a payload-carrying projectile
Projectile
A projectile is any object projected into space by the exertion of a force. Although a thrown baseball is technically a projectile too, the term more commonly refers to a weapon....

, which, as opposed to shot
Round shot
Round shot is a solid projectile without explosive charge, fired from a cannon. As the name implies, round shot is spherical; its diameter is slightly less than the bore of the gun it is fired from.Round shot was made in early times from dressed stone, but by the 17th century, from iron...

, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot (AP, APCR, APCNR, APDS, APFSDS and proof shot). Solid shot may contain a pyrotechnic compound if a tracer
Tracer ammunition
Tracer ammunition are bullets that are built with a small pyrotechnic charge in their base. Ignited by the burning powder, the phosphorus tail burns very brightly, making the projectile visible to the naked eye...

 or spotting charge is used. Originally "bombshell", but "shell" has come to be unambiguous in a military context.
Encyclopedia
A shell is a payload-carrying projectile
Projectile
A projectile is any object projected into space by the exertion of a force. Although a thrown baseball is technically a projectile too, the term more commonly refers to a weapon....

, which, as opposed to shot
Round shot
Round shot is a solid projectile without explosive charge, fired from a cannon. As the name implies, round shot is spherical; its diameter is slightly less than the bore of the gun it is fired from.Round shot was made in early times from dressed stone, but by the 17th century, from iron...

, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot (AP, APCR, APCNR, APDS, APFSDS and proof shot). Solid shot may contain a pyrotechnic compound if a tracer
Tracer ammunition
Tracer ammunition are bullets that are built with a small pyrotechnic charge in their base. Ignited by the burning powder, the phosphorus tail burns very brightly, making the projectile visible to the naked eye...

 or spotting charge is used. Originally "bombshell", but "shell" has come to be unambiguous in a military context. "Bombshell" is still used figuratively to refer to a shockingly unexpected happening.

All explosive and incendiary filled projectiles, particularly for mortars
Mortar (weapon)
A mortar is an indirect fire weapon that fires explosive projectiles known as bombs at low velocities, short ranges, and high-arcing ballistic trajectories. It is typically muzzle-loading and has a barrel length less than 15 times its caliber....

, were originally called grenades, derived from the pomegranate due to its seeds being similar to grains of powder. Words cognate to grenade are still used for an artillery or mortar projectile in some European languages.

Shells are usually large calibre projectiles fired by 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...

 and combat vehicle
Combat vehicle
A combat vehicle, also known as a ground combat vehicle, is a self-propelled, weaponized military vehicle used for combat operations. Combat vehicles can be wheeled or tracked.- Automation :...

s (including tank
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

s), and warship
Warship
A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuvrable than merchant ships...

s.

Shells usually have the shape of a cylinder
Cylinder (geometry)
A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...

 topped by an ogive
Ogive
An ogive is the roundly tapered end of a two-dimensional or three-dimensional object.-Applied physical science and engineering:In ballistics or aerodynamics, an ogive is a pointed, curved surface mainly used to form the approximately streamlined nose of a bullet or other projectile.The traditional...

-shaped nose for good aerodynamic performance, possibly with a tapering base; but some specialized types are quite different.

History

Solid cannonballs (“shot”) did not need a fuze
Artillery fuze
An artillery fuze or artillery fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns , howitzers and mortars. A fuze is a device that initiates an explosive function in a munition, most commonly causing it to detonate or release its contents, when its...

, but hollow balls (“shells”) filled with something, such as gunpowder to fragment the ball needed a fuze, either impact (or percussion) or time. Percussion fuzes with a spherical projectile presented a challenge because there was no way of ensuring that the impact mechanism hit the target. Therefore shells needed a time fuze that was ignited before or during firing and burnt until the shell reached its target. Early reports of shells include Venetian use at Jadra in 1376 and shells with fuzes at the 1421 siege of St Boniface in Corsica. These were two hollowed hemispheres of stone or bronze held together by an iron hoop. Written evidence for early explosive shells in China appears in the early Ming Dynasty
Ming Dynasty
The Ming Dynasty, also Empire of the Great Ming, was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history", was the last dynasty in China ruled by ethnic...

 (1368–1644) Chinese
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 military manual Huolongjing
Huolongjing
The Huolongjing is a 14th century military treatise that was compiled and edited by Jiao Yu and Liu Ji of the early Ming Dynasty in China...

, compiled by Jiao Yu
Jiao Yu
Jiao Yu was a Chinese military officer loyal to Zhu Yuanzhang , the founder of the Ming Dynasty . He was entrusted by Emperor Hongwu as a leading artillery officer for the rebel army that overthrew the Mongol Yuan Dynasty, and established the Ming Dynasty...

 (fl.
Floruit
Floruit , abbreviated fl. , is a Latin verb meaning "flourished", denoting the period of time during which something was active...

 14th to early 15th century) and Liu Ji (1311–1375) sometime before the latter's death, a preface added by Jiao in 1412. As described in their book, these hollow, gunpowder-packed shells were made of cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

.

Yi jang-son made Bigyukjincheonroi in the reign of Seonjo of Joseon
Seonjo of Joseon
King Seonjo ruled in Korea between 1567 and 1608. He was the fourteenth king of the Joseon Dynasty. He is known for encouraging Confucianism and renovating state affairs at the beginning of his reign, although political chaos and his incompetent leadership during the Japanese invasions of Korea...

. (WP:CIRCULAR and WP:RSUE) Bigyukjincheonroi is a time shell that consisted of wooden tube wound with time fuze made of thread, iron scrap and cap. Its time fuze can be set the time by length of thread. It was used in Japanese invasions of Korea. They were usually fired from the family of wan-gu (Hangul
Hangul
Hangul,Pronounced or ; Korean: 한글 Hangeul/Han'gŭl or 조선글 Chosŏn'gŭl/Joseongeul the Korean alphabet, is the native alphabet of the Korean language. It is a separate script from Hanja, the logographic Chinese characters which are also sometimes used to write Korean...

: 완구; Hanja
Hanja
Hanja is the Korean name for the Chinese characters hanzi. More specifically, it refers to those Chinese characters borrowed from Chinese and incorporated into the Korean language with Korean pronunciation...

: 碗口; literally "bowl-mouth") mortars.

An early problem was that until 1672 there was no means of measuring the time precisely
Accuracy and precision
In the fields of science, engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which...

 enough—clockwork fuzes did not yet exist. The burning time of the powder fuze was subject to considerable trial and error. Early powder burning fuzes had to be loaded fuze down to be ignited by firing or a portfire put down the barrel to light the fuze. Other shells were wrapped in bitumen cloth which would ignite during the firing and in turn ignite a powder fuse. However, by the 18th Century it was discovered that the fuze towards the muzzle could be lit by the flash through the windage between shell and barrel. Nevertheless, shells came into regular use in the 16th Century, for example a 1543 English mortar shell filled with 'wildfire'. About 1700 shells began to be employed for horizontal fire from howitzers with a small propelling charge and in 1779 experiments demonstrated that they could be used from guns with heavier charges. They became usual with field artillery early in the 19th Century. By this time shells were usually cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

, but bronze, lead, brass and even glass were tried.

The history of artillery fuzes is given in that article
Artillery fuze
An artillery fuze or artillery fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns , howitzers and mortars. A fuze is a device that initiates an explosive function in a munition, most commonly causing it to detonate or release its contents, when its...

.

Cast-iron spherical common shell (so named because they were used against "common" [usual] targets) were in use up to 1871. Typically the thickness of the metal body was about 1/6 their diameter and they were about 2/3s the weight of solid shot of the same calibre. In order to ensure that shells were loaded with their fuzes towards the muzzle they were attached to wooden bottoms called 'sabots'. In 1819 a committee of British artillery officers recognised that they were essential stores and in 1830 Britain standardised sabot thickness as half inch. The sabot also intended to reduce jamming during loading and the rebounding of the shell as it traveled along the bore on discharge. Mortar shells were not fitted with sabot
Sabot
A sabot is a device used in a firearm or cannon to fire a projectile, such as a bullet, that is smaller than the bore diameter, or which must be held in a precise position. The term is also applied to a battery stub case, a device used similarly to make a small electrical battery usable in a...

s.

Rifling was invented by Jaspard Zoller, a Viennese gun maker at the end of the 15th Century, and it was realised that twisted rifling to spin an elongated projectile would greatly improve its accuracy. This was known to artillerists but its application to artillery was beyond the available technology until around the mid 19th Century. English inventor notable Armstrong, Whitworth and Lancaster and the latter's rifled guns were used in the Crimean War. Armstrong's rifled breech-loading
Breech-loading weapon
A breech-loading weapon is a firearm in which the cartridge or shell is inserted or loaded into a chamber integral to the rear portion of a barrel....

 cannon was a key innovation and adopted for British service in 1859. Also in the 1850s rifled guns were developed by Major Cavelli in Italy, Baron Wahrendorff and Krupp in Germany and the Wiard gun in the United States. However, rifled barrels required some means of engaging the shell with the rifling. Lead coated shells were used with Armstrong guns, but were not satisfactory so studded projectiles were adopted. However these did not seal the gap between shell and barrel. Wads at the shell base were tried, without success, in 1878 the British adopted a copper 'gas-check
Gas check
A gas check is a device used in some types of firearms ammunition. Gas checks are used when non-jacketed bullets are used in high pressure cartridges, to prevent the buildup of lead in the barrel and aid in accuracy.-Construction:...

' at the base of their studded projectiles, and in 1879 tried a rotating gas check to replace the studs, leading to the 1881 automatic gas-check. This was soon followed by the Vavaseur copper driving band as part of the projectile. The driving band rotated the projectile, centred it in the bore and prevented gas escaping forwards. A driving band has to be soft but tough enough to prevent stripping by rotational and engraving stresses. Copper is generally most suitable but cupro nickel or gilding metal are also used.

The first pointed armour piercing shell was introduced by Major Palliser in 1863, it was made of chilled cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 with an ogival head of 1 calibres radius. However, during 1880–1890 steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 shells and armour began to appear and it was realised that steel bodies for explosive filled shells had advantages - better fragmentation and resistance to the stresses of firing. These were cast and forged steel.

Shells have never been limited to an explosive filling. An incendiary shell was invented by Valturio in 1460. The carcass was invented in 1672 by a gunner serving Christoph van Galen, Prince Bishop of Munster, initially oblong in an iron frame or carcass (with poor ballistic properties) it evolved into a spherical shell. Their use continued well into the 19th Century. In 1857 the British introduced a incendiary shell (Martin's) filled with molten iron, which replaced red hot shot used against ships, most notably at Gibraltar in 1782. Two patterns of incendiary shell were used by the British in World War 1, one designed for use against Zeppelins.

Similar to incendiary shells were star shells, designed for illumination rather than arson. Sometimes called lightballs they were in use from the 17th Century onwards. The British adopted parachute lightballs in 1866 for 10, 8 and 5 inch calibres. The 10-inch wasn't officially declared obsolete until 1920!

Smoke balls also date back to the 17th Century, British ones contained a mix of saltpetre, coal, pitch, tar, resin, sawdust, crude antimony and sulphur. They produced a 'noisome smoke in abundance that is impossible to bear'. In the 19th Century British service they were made of concentric paper with thickness about 1/15th of total diameter and filled with powder, saltpetre, pitch, coal and tallow. They were used to 'suffocate or expel the enemy in casemates, mines or between decks; for concealing operations; and as signals.

During the First World War, shrapnel shells and explosive shells inflicted terrible casualties on infantry, accounting for nearly 70% of all war casualties and leading to the adoption of steel helmet
Helmet
A helmet is a form of protective gear worn on the head to protect it from injuries.Ceremonial or symbolic helmets without protective function are sometimes used. The oldest known use of helmets was by Assyrian soldiers in 900BC, who wore thick leather or bronze helmets to protect the head from...

s on both sides. Shells filled with poison gas were used from 1917 onwards. Frequent problems with shells led to many military disasters when shells failed to explode, most notably during the 1916 Battle of the Somme.

Sizes

The calibre of a shell is its diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...

. Depending on the historical period and national preferences, this may be specified in millimetres, centimetres, or inches. The length of gun barrels for large cartridges
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

 and shells (naval) is frequently quoted in terms of calibre. [1] Some guns, mainly British, were specified by the weight of their shells (see below).

Due to manufacturing difficulties the smallest shells commonly used are around 20 mm calibre, used in aircraft cannon and on armoured vehicles. Smaller shells are only rarely used as they are difficult to manufacture and can only have a small explosive charge. The largest shells ever fired were those from the German super-railway gun
Railway gun
A railway gun, also called a railroad gun, is a large artillery piece, often surplus naval ordnance, mounted on, transported by, and fired from a specially designed railway wagon. Many countries have built railway guns, but the best known are the large Krupp-built pieces used by Germany in World...

s, Gustav and Dora
Schwerer Gustav
Schwerer Gustav and Dora were the names of two massive World War II German 80 cm K railway siege guns. They were developed in the late 1930s by Krupp for the express purpose of destroying heavy fortifications, specifically those in the French Maginot Line...

, which were 800 mm (31.5") in calibre. Very large shells have been replaced by rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...

s, guided missile
Guided Missile
Guided Missile is a London based independent record label set up by Paul Kearney in 1994.Guided Missile has always focused on 'the underground', preferring to put out a steady flow of releases and developing the numerous GM events around London and beyond....

, and bombs, and today the largest shells in common use are 155 mm (6.1").

Gun calibres have standardized around a few common sizes, especially in the larger range, mainly due to the uniformity required for efficient military logistics. Shells of 105, 120, and 155 mm diameter are common for NATO forces' artillery and tank gun
Tank gun
A tank gun is the main armament of a tank. Modern tank guns are large-caliber high-velocity guns, capable of firing kinetic energy penetrators, high explosive anti-tank rounds, and in some cases guided missiles. Anti-aircraft guns can also be mounted to tanks.-Overview:Tank guns are a specific...

s. Artillery shells of 122, 130 and 152 mm, and tank gun ammunition of 100, 115, or 125 mm calibre remain in use in Eastern Europe and China. Most common calibres have been in use for many years, since it is logistically
Logistics
Logistics is the management of the flow of goods between the point of origin and the point of destination in order to meet the requirements of customers or corporations. Logistics involves the integration of information, transportation, inventory, warehousing, material handling, and packaging, and...

 complex to change the calibre of all guns and ammunition stores.

The weight of shells increases by and large with calibre. A typical 150 mm (5.9") shell weighs about 50 kg, a common 203 mm (8") shell about 100 kg, a concrete demolition 203 mm (8") shell 146 kg, a 280 mm (11") battleship shell about 300 kg, and a 460 mm (18") battleship shell over 1500 kg. The Schwerer Gustav
Schwerer Gustav
Schwerer Gustav and Dora were the names of two massive World War II German 80 cm K railway siege guns. They were developed in the late 1930s by Krupp for the express purpose of destroying heavy fortifications, specifically those in the French Maginot Line...

 supergun
Supergun
A supergun is an extraordinarily large artillery piece. This size may be due to a large bore, barrel length or a combination of the two. While early examples tended to have a fairly short range more recent examples sometimes had an extremely high muzzle velocity resulting in a very long...

 fired 4.8 and 7.1 tonne shells.

Old-style British classification by weight

During the 19th Century the British adopted a particular form of designating artillery. Guns were designated by nominal standard projectile weight while Howitzers were designated by barrel calibre. British Guns and their ammunition were designated in pound
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

s, e.g., as "two-pounder" shortened to "2-pr" or "2-pdr". Usually this referred to the actual weight of the standard projectile (shot, shrapnel or HE), but, confusingly, this was not always the case. Some were named after the weights of obsolete projectile types of the same calibre, or even obsolete types that were considered to have been functionally equivalent. Also, projectiles fired from the same gun, but of non-standard weight, took their name from the gun. Thus, conversion from "pounds" to an actual barrel diameter requires consulting a historical reference. Since the creation of NATO new British guns are designated by calibre.

High-explosive

The most common shell type is high explosive, commonly referred to simply as HE. They have a strong steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 case, a bursting charge, and a fuze
Artillery fuze
An artillery fuze or artillery fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns , howitzers and mortars. A fuze is a device that initiates an explosive function in a munition, most commonly causing it to detonate or release its contents, when its...

. The fuze detonates the bursting charge which shatters the case and scatters hot, sharp case pieces (fragments, splinters) at high velocity. Most of the damage to soft targets such as unprotected personnel is caused by shell pieces rather than by the blast. The term "shrapnel" is sometimes incorrectly used to describe the shell pieces, but shrapnel shells functioned very differently and are long obsolete. Depending on the type of fuze
Artillery fuze
An artillery fuze or artillery fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns , howitzers and mortars. A fuze is a device that initiates an explosive function in a munition, most commonly causing it to detonate or release its contents, when its...

 used the HE shell can be set to burst on the ground (percussion), in the air above the ground (time or proximity), or after penetrating a short distance into the ground (percussion with delay, either to transmit more ground shock to covered positions, or to reduce the spread of fragments).

Early high explosives used before and during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 in HE shells were Lyddite (picric acid), PETN
PETN
Pentaerythritol tetranitrate , also known as PENT, PENTA, TEN, corpent, penthrite , is the nitrate ester of pentaerythritol. Penta refers to the five carbon atoms of the neopentane skeleton.PETN is most well known as an explosive...

, TNT. However, pure TNT was expensive to produce and most nations made some use of mixtures using cruder TNT and ammonium nitrate, some with other compounds included. These fills included Ammonal, Schneiderite and Amatol
Amatol
Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. Its name originates from the words ammonium and toluene...

. The latter was still in wide use in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

.

From 1944 to 1945 RDX
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

 and TNT mixtures became standard. Notably "Composition B" (cyclotol)
Composition B
Composition B, colloquially "comp B", is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades, sticky bombs and various other munitions...

. The introduction of 'insensitive munition' requirements, agreements and regulations in the 1990s caused modern western designs to use various types of plastic bonded explosives (PBX) based on RDX.

The percentage of shell weight taken up by its explosive fill increased steadily throughout the 20th Century. Less than 10% was usual in the first few decades, by World War II leading designs were around 15%. However, British researchers in that war identified 25% as being the optimal design for anti-personnel purposes, based on recognition that far smaller fragments than hitherto would give the required effects. This was achieved by 1960s designed 155mm L15 shell developed as part of the FH-70
FH-70
The FH-70 is a towed howitzer in use with several nations.-History:In 1963 NATO agreed a NATO Basic Military Requirement 39 for close support artillery, either towed or tracked. Subsequently Germany and UK started discussions and design studies and in 1968 established Agreed Operational...

 program. The key requirement for increasing the HE content without increasing shell weight was to reduce the thickness of shell walls, this required improvements in high tensile steel.

Mine shell

The mine shell is a particular form of HE shell developed for use in small caliber weapons such as 20 mm to 30 mm cannon. Small HE shells of conventional design can contain only a limited amount of explosive. By using a thin-walled steel casing of high tensile strength, a larger explosive charge can be used. Most commonly the explosive charge also was a more expensive but higher-detonation-energy type. The mine shell concept was invented by the Germans in the Second World War primarily for use in aircraft guns intended to be fired at opposing aircraft. Mine shells produced relatively little damage due to fragments, but a much more powerful blast. The aluminium structures and skins of Second World War aircraft were readily damaged by this greater level of blast.

Armour-piercing

The earliest naval and anti-tank shells had to withstand the extreme shock of punching through armour plate. Shells designed for this purpose sometimes had a greatly strengthened case with a small bursting charge, and sometimes were solid metal, i.e. shot
Round shot
Round shot is a solid projectile without explosive charge, fired from a cannon. As the name implies, round shot is spherical; its diameter is slightly less than the bore of the gun it is fired from.Round shot was made in early times from dressed stone, but by the 17th century, from iron...

. In either case, they almost always had a specially hardened and shaped nose to facilitate penetration. This resulted in armour-piercing (AP) projectiles.

A further refinement of such designs improved penetration by adding a softer metal cap to the penetrating nose giving armour-piercing, capped (APC) design. The softer cap dampens the initial shock that would otherwise shatter the round. The best profile for the cap is not the most aerodynamic; this can be remedied by adding a further hollow cap of suitable shape: APCBC
APCBC
The armour-piercing capped ballistic cap is a type of armor-piercing shell introduced in the 1930s.-Development:The APCBC munition type was an evolutionary development of the early war armour-piercing capped shell, itself an evolution of the more basic AP and APHE shell types...

 (APC + ballistic cap).

AP shells with a bursting charge were sometimes distinguished by appending the suffix "HE". At the beginning of the Second World War, solid shot AP projectiles were common. As the war progressed, ordnance design evolved so that APHE became the more common design approach for anti-tank shells of 75 mm caliber and larger, and more common in naval shell design as well. In modern ordnance, most full caliber AP shells are APHE designs.

Armour-piercing, discarding-sabot

Armour-piercing, discarding-sabot (APDS) was developed by engineers working for the French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 Edgar Brandt
Edgar Brandt
Edgar William Brandt was a French ironworker, prolific weapons designer and head of a company that designed 60mm, 81mm and 120mm mortars that were very widely copied throughout and subsequent to World War II...

 company, and was fielded in two calibers (75 mm/57 mm for the Mle1897/33 anti-tank cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...

, 37 mm/25 mm for several 37 mm gun types) just before the French-German armistice of 1940. The Edgar Brandt
Edgar Brandt
Edgar William Brandt was a French ironworker, prolific weapons designer and head of a company that designed 60mm, 81mm and 120mm mortars that were very widely copied throughout and subsequent to World War II...

 engineers, having been evacuated to the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, joined ongoing APDS development efforts there, culminating in significant improvements to the concept and its realization. British APDS ordnance for their QF 6 pdr
Ordnance QF 6 pounder
The Ordnance Quick-Firing 6-pounder 7 cwt, or just 6 pounder, was a British 57 mm gun, their primary anti-tank gun during the middle of World War II, as well as the main armament for a number of armoured fighting vehicles...

 and 17 pdr anti-tank guns was fielded in March 1944.

The armour-piercing concept calls for more penetration capability than the target's armour thickness. Generally, the penetration capability of an armor piercing round is proportional to the projectile's kinetic energy. Thus an efficient means of achieving increased penetrating power is increased velocity for the projectile. However, projectile impact against armour at higher velocity causes greater levels of shock. Materials have characteristic maximum levels of shock capacity, beyond which they may shatter on impact. At relatively high impact velocities, steel is no longer an adequate material for armor piercing rounds due to shatter. Tungsten and tungsten alloys are suitable for use in even higher velocity armour piercing rounds due to their very high shock tolerance and shatter resistance. However, tungsten is very dense, and tungsten rounds of full-caliber design are too massive to be accelerated to an efficient velocity for maximized kinetic energy. This is overcome by using a reduced-diameter tungsten shot, surrounded by a lightweight outer carrier, the sabot (a French word for a wooden shoe). This combination allows the firing of a smaller diameter (thus lower mass/aerodynamic resistance/penetration resistance) projectile with a larger area of expanding-propellant "push", thus a greater propelling force/acceleration/resulting kinetic energy.

Once outside the barrel, the sabot is stripped off by a combination of centrifugal force
Centrifugal force
Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...

 and aerodynamic force, giving the shot low drag in flight. For a given caliber the use of APDS ammunition can effectively double the anti-tank performance of a gun.

Armour-piercing, fin-stabilized, discarding-sabot

An Armour-Piercing, Fin-Stabilised, Discarding Sabot (APFSDS
Kinetic energy penetrator
A kinetic energy penetrator is a type of ammunition which, like a bullet, does not contain explosives and uses kinetic energy to penetrate the target....

) projectile uses the sabot principle with fin (drag) stabilisation. A long, thin sub-projectile has increased sectional density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

 and thus penetration potential. However, once a projectile has a length-to-diameter ratio greater than 10 (less for higher density projectiles), spin stabilisation becomes ineffective. Instead, drag stabilisation is used, by means of fins attached to the base of the sub-projectile, making it look like a large metal arrow.

Large calibre APFSDS projectiles are usually fired from smooth-bore (unrifled) barrels, though they can be and often are fired from rifled guns. This is especially true when fired from small to medium calibre weapon systems. APFSDS projectiles are usually made from high-density metal alloys such as tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...

 heavy alloys (WHA) or depleted uranium
Depleted uranium
Depleted uranium is uranium with a lower content of the fissile isotope U-235 than natural uranium . Uses of DU take advantage of its very high density of 19.1 g/cm3...

  (DU); maraging steel
Maraging steel
Maraging steels are steels which are known for possessing superior strength and toughness without losing malleability, although they cannot hold a good cutting edge. Aging refers to the extended heat-treatment process...

 was used for some early Soviet projectiles. DU alloys are cheaper and have better penetration than others as they are denser and self-sharpening. Uranium is also pyrophoric and may become opportunistic incendiaries especially as the round shears
Adiabatic shear band
Adiabatic shear band is a term used in physics, mechanics and engineering.Since the 1960s adiabatic shear bands have been studied extensively because of their importance as a failure mode in areas such as metal forming and cutting, various types of ballistic impact, as well as vehicle crashes.An...

 past the armor exposing non-oxidized metal, but both the metal's fragments and dust contaminate the battlefield with toxic hazards. The less toxic WHAs are preferred in most countries except the USA, UK, and Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

.

Armour-piercing, composite rigid

Armour-piercing, composite rigid (APCR) is a British term, the US term for the design is high velocity armor piercing (HVAP) and German, Hartkernmunition. The APCR projectile is a core of a high-density hard material such as tungsten carbide
Tungsten carbide
Tungsten carbide is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...

 surrounded by a full-bore shell of a lighter material (e.g. an aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 alloy). Most APCR projectiles are shaped like the standard APCBC shot (although some of the German Pzgr. 40 and some Soviet designs resemble a stubby arrow), but the projectile is lighter: up to half the weight of a standard AP shot of the same calibre. The lighter weight allows a higher velocity. The kinetic energy of the shot is concentrated in the core and hence on a smaller impact area, improving the penetration of the target armour. To prevent shattering on impact, a shock-buffering cap is placed between the core and the outer ballistic shell as with APC rounds. However, because the shot is lighter but still the same overall size it has poorer ballistic qualities, and loses velocity and accuracy at longer ranges. The APCR was superseded by the APDS which dispensed with the outer light alloy shell once the shot had left the barrel.
The Germans used an APCR round, the Panzergranate 40 (Pzgr.40) "arrowhead" shot, for their 5 cm Pak 38 antitank guns in 1942, and it was also developed for their 75 and 88 mm antitank and tank guns, and for anti-tank guns mounted in German aircraft. Shortages of the key component, tungsten, led to the Germans dropping the use of APCR during late World War II because tungsten was more efficiently used in industrial applications such as machine tools.

Armour-piercing, composite non-rigid

Armour-piercing, composite non-rigid (APCNR), the British term, but the more common terms are squeeze-bore and tapered bore and are based on the same projectile design as the APCR - a high density core within a shell of soft iron or other alloy, but it is fired by a gun with a tapered barrel, either a taper in a fixed barrel (Gerlich design in German use; original development efforts in the late 1930s in Germany, Denmark and France) or a final added section as in the British Littlejohn adaptor
Littlejohn adaptor
The Littlejohn adaptor was a device that could be added to the British QF 2 pounder anti-tank gun. It was used to extend the service life of the 2-pounder during the Second World War by converting it to squeeze bore operation...

. The projectile is initially full-bore, but the outer shell is deformed as it passes through the taper. Flanges or studs are swaged down in the tapered section, so that as it leaves the muzzle the projectile has a smaller overall cross-section. This gives it better flight characteristics with a higher sectional density and the projectile retains velocity better at longer ranges than an undeformed shell of the same weight. As with the APCR the kinetic energy of the round is concentrated at the core on impact. The initial velocity of the round is greatly increased by the decrease of barrel cross-sectional area toward the muzzle, resulting in a commensurate increase in velocity of the expanding propellant gases.
The Germans deployed their initial design as a light anti-tank weapon, 2,8 cm schwere Panzerbüchse 41
2.8 cm sPzB 41
2.8 cm schwere Panzerbüchse 41 or "Panzerbüchse 41" was a German anti-tank weapon working on the squeeze bore principle. Officially classified as heavy anti-tank rifle , it would be better described, and is widely referred to, as a light anti-tank gun.-Description:Although the sPzB 41 was...

, early in the Second World War, and followed on with the 4.2 cm Pak 41
4.2 cm PaK 41
The 4.2 cm Pak 41 was a light anti-tank gun issued to German airborne units in World War II. This gun was externally similar to the 3.7 cm Pak 36, and used a modified version of the latter's carriage, but used the squeeze bore principle to boost its velocity,...

 and 7.5 cm Pak 41
7.5 cm PaK 41
The 7.5 cm PaK 41 was one of the last German anti-tank guns brought into service and used in World War II and notable for being one of the largest anti-tank guns to rely on the Gerlich principle to deliver a higher muzzle velocity and therefore greater penetration in...

. Although HE projectiles were designed and put into service, they weighed 85 grams and had low effectiveness. The British used the Littlejohn squeeze-bore adaptor which could be attached or removed as necessary. The adaptor extended the usefulness of armoured cars and light tanks which could not fit any gun larger than the QF 2 pdr
Ordnance QF 2 pounder
The Ordnance QF 2-pounder was a British anti-tank and vehicle-mounted gun, employed in the Second World War. It was actively used in the Battle of France, and during the North Africa campaign...

. Although a full range of shells and shot could be used, changing the adaptor in the heat of battle was highly impractical. The APCNR was superseded by the APDS design which was compatible with non-tapered barrels.

High-explosive, anti-tank

HEAT
High explosive anti-tank
High explosive anti-tank warheads are made of an explosive shaped charge that uses the Munroe effect to create a very high-velocity partial stream of metal in a state of superplasticity that can punch through solid armor....

 shells are a type of shaped charge
Shaped charge
A shaped charge is an explosive charge shaped to focus the effect of the explosive's energy. Various types are used to cut and form metal, to initiate nuclear weapons, to penetrate armor, and in the oil and gas industry...

 used to defeat armoured vehicles. They are extremely efficient at defeating plain steel armour but less so against later composite and reactive armour
Reactive armour
Reactive armour is a type of vehicle armour that reacts in some way to the impact of a weapon to reduce the damage done to the vehicle being protected. It is most effective in protecting against shaped charges and specially hardened long rod penetrators...

. The effectiveness of the shell is independent of its velocity, and hence the range: it is as effective at 1000 metres as at 100 metres. The speed can even be zero in the case where a soldier simply places a magnetic mine onto a tank's armor plate. A HEAT charge is most effective when detonated at a certain, optimal, distance in front of the target and HEAT shells are usually distinguished by a long, thin nose probe sticking out in front of the rest of the shell and detonating it at the correct distance, e.g., PIAT
PIAT
The Projector, Infantry, Anti Tank was a British hand-held anti-tank weapon developed during the Second World War. The PIAT was designed in 1942 in response to the British Army's need for a more effective infantry anti-tank weapon, and entered service in 1943.The PIAT was based on the spigot...

 bomb. HEAT shells are less effective if spun (i.e., fired from a rifled gun).

Discarding-sabot shell

A discarding-sabot shell (DSS) is (in principle) the same as the APDS shot but applied to high-explosive shells. It is a means to deliver a shell to a greater range. The design of the sub-projectile carried inside the sabot can be optimised for aerodynamic properties and the sabot can be built for best performance within the barrel of the gun. The principle was developed by a Frenchman, Edgar Brandt
Edgar Brandt
Edgar William Brandt was a French ironworker, prolific weapons designer and head of a company that designed 60mm, 81mm and 120mm mortars that were very widely copied throughout and subsequent to World War II...

, in the 1930s. With the occupation of France, the Germans took the idea for application to anti-aircraft guns—a DSS projectile could be fired at a higher muzzle velocity and reach the target altitude more quickly, simplifying aiming and allowing the target aircraft less time to change course.

High-explosive, squash-head or high-explosive plastic

High-explosive, squash-head (HESH) is another anti-tank shell based on the use of explosive. Developed by the British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 inventor Sir Charles Dennistoun Burney
Charles Dennistoun Burney
Sir Charles Dennistoun Burney, 2nd Baronet was an English aeronautical engineer, private inventor and Conservative Party politician....

 in World War II for use against fortifications. A thin-walled shell case contains a large charge of a plastic explosive
Plastic explosive
Plastic explosive is a specialised form of explosive material. It is a soft and hand moldable solid material. Plastic explosives are properly known as putty explosives within the field of explosives engineering....

. On impact the explosive flattens, without detonating, against the face of the armour, and is then detonated by the fuze. Energy is transferred through the armour plate: when the compressive shock reflects off the air/metal interface on the inner face of the armour, it is transformed into a tension wave which spall
Spall
Spall are flakes of a material that are broken off a larger solid body and can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure...

s a "scab" of metal off into the tank damaging the equipment and crew without actually penetrating the armour.

HESH is completely defeated by spaced armour
Spaced armour
Armour with two or more plates spaced a distance apart is called spaced armour. When sloped it reduces the penetrating power of bullets and solid shot as after penetrating each plate they tend to tumble, deflect, deform, or disintegrate; when not sloped it increases the protection offered by the...

, so long as the plates are individually able to withstand the explosion. It is still considered useful as not all vehicles are equipped with spaced armour, and it is also the most effective munition for demolishing brick and concrete. HESH shells, unlike HEAT shells, are best fired from rifled guns.

Another variant is the high-explosive plastic (HEP).

Proof shot

A proof shot is not used in combat but to confirm that a new gun barrel can withstand operational stresses. The proof shot is heavier than a normal shot or shell, and an oversize propelling charge is used, subjecting the barrel to greater than normal stress. The proof shot is inert (no explosive or functioning filling) and is often a solid unit, although water, sand or iron powder filled versions may be used for testing the gun mounting. Although the proof shot resembles a functioning shell (of whatever sort) so that it behaves as a real shell in the barrel, it is not aerodynamic as its job is over once it has left the muzzle of the gun. Consequently it travels a much shorter distance and is usually stopped by an earth bank for safety measures.

The gun, operated remotely for safety in case it fails, fires the proof shot, and is then inspected for damage. If the barrel passes the examination "proof marks" are added to the barrel. The gun can be expected to handle normal ammunition, which subjects it to less stress than the proof shot, without being damaged.

Shrapnel shells


Shrapnel shells were an early (1784) anti-personnel munition which delivered large numbers of bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...

s at ranges far greater than rifles or machine guns could attain - up to 6,500 yards by 1914. A typical shrapnel shell as used in World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 was streamlined, 75 mm (3 inch) in diameter and contained approximately 300 lead-antimony balls (bullets), each approximately 1/2 inch in diameter. Shrapnel used the principle that the bullets encountered much less air resistance if they travelled most of their journey packed together in a single streamlined shell than they would if they travelled individually, and could hence attain a far greater range.

The gunner set the shell's time fuze so that it was timed to burst as it was angling down towards the ground just before it reached its target (ideally about 150 yards before, and 60–100 feet above the ground). The fuze then ignited a small "bursting charge" in the base of the shell which fired the balls forward out of the front of the shell case, adding approximately 200 – 250 ft/second to the existing velocity of 750–1200  ft/second. The shell body dropped to the ground mostly intact and the bullets continued in an expanding cone shape before striking the ground over an area approximately 250 yards × 30 yards in the case of the US 3 inch shell. The effect was of a large shotgun blast just in front of and above the target, and was deadly against troops in the open. A trained gun team could fire 20 such shells per minute, with a total of 6,000 balls, which compared very favourably with rifles and machine-guns.

However, shrapnel's relatively flat trajectory (it depended mainly on the shell's velocity for its lethality, and was only lethal in a forward direction) meant that it could not strike trained troops who avoided open spaces and instead used dead ground (dips), shelters, trenches, buildings, and trees for cover. It was of no use in destroying buildings or shelters. Hence it was replaced during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 by the high-explosive shell which exploded its fragments in all directions and could be fired by high-angle weapons such as howitzers, hence far more difficult to avoid.

Cluster shells

Cluster shells are a type of carrier shell or cargo munition. Like cluster bomb
Cluster bomb
A cluster munition is a form of air-dropped or ground-launched explosive weapon that releases or ejects smaller sub-munitions. Commonly, this is a cluster bomb that ejects explosive bomblets that are designed to kill enemy personnel and destroy vehicles...

s, an artillery shell may be used to scatter smaller submunitions, including anti-personnel grenade
Grenade
A grenade is a small explosive device that is projected a safe distance away by its user. Soldiers called grenadiers specialize in the use of grenades. The term hand grenade refers any grenade designed to be hand thrown. Grenade Launchers are firearms designed to fire explosive projectile grenades...

s, anti-tank top-attack munitions, and landmines
Land mine
A land mine is usually a weight-triggered explosive device which is intended to damage a target—either human or inanimate—by means of a blast and/or fragment impact....

. These are generally far more lethal against both armor
Armoured fighting vehicle
An armoured fighting vehicle is a combat vehicle, protected by strong armour and armed with weapons. AFVs can be wheeled or tracked....

 and 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...

 than simple high-explosive shells, since the multiple munitions create a larger kill zone and increase the chance of achieving the direct hit necessary to kill armor. Most modern armies make significant use of cluster munitions in their artillery batteries.

However, in operational use submunitions have demonstrated a far higher malfunction rate than previously claimed, including those that have self-destruct mechanisms. This problem, the 'dirty battlefield", led to the Ottawa Treaty
Ottawa Treaty
The Ottawa Treaty or the Anti-Personnel Mine Ban Convention, officially known as the Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction, aims at eliminating anti-personnel landmines around the world. , there were 158...

.

Artillery-scattered mines allow for the quick deployment of minefields into the path of the enemy without placing engineering units at risk, but artillery delivery may lead to an irregular and unpredictable minefield with more unexploded ordnance than if mines were individually placed.

Signatories of the Ottawa Treaty
Ottawa Treaty
The Ottawa Treaty or the Anti-Personnel Mine Ban Convention, officially known as the Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction, aims at eliminating anti-personnel landmines around the world. , there were 158...

 have renounced the use of cluster munitions of all types where the carrier contains more than ten submunitions.

Chemical

Chemical shells contain just a small explosive charge to burst the shell, and a larger quantity of a chemical agent such as a poison gas. Signatories of the Chemical Weapons Convention
Chemical Weapons Convention
The Chemical Weapons Convention is an arms control agreement which outlaws the production, stockpiling and use of chemical weapons. Its full name is the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction...

 have renounced such shells.

Non-lethal shells

Not all shells are designed to kill or destroy. The following types are designed to achieve particular non-lethal effects. They are not completely harmless: smoke and illumination shells can accidentally start fires, and impact by the discarded carrier of all three types can wound or kill personnel, or cause minor damage to property.

Smoke

The smoke shell is designed to create a smoke screen. The main types are bursting (those filled with white phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 WP and a small HE bursting charge are best known) and base ejection (delivering three or four smoke canisters, or material impregnated with white phosphorus). Base ejection shells are a type of carrier shell or cargo munition.

Base ejection smoke is usually white, however, coloured smoke has been used for marking purposes. The original canisters were non-burning, being filled with a compound that created smoke when it reacted with atmospheric moisture, modern ones use red phosphorus because of its multi-spectral properties. However, other compounds have been used, in World War II Germany used oleum (fuming sulphuric acid) and pumice.

Illumination

Modern illuminating shells are a type of carrier shell or cargo munition. Those used in World War I were shrapnel pattern shells ejecting small burning 'pots'.

A modern illumination shell has a fuze which ejects the "candle" (a pyrotechnic
Pyrotechnics
Pyrotechnics is the science of using materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...

 flare emitting white or infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 light) at a calculated altitude, where it slowly drifts down beneath a heat resistant parachute
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...

, illuminating the area below. These are also known as starshell or star shell.

Coloured flare shells have also been used for target marking purposes.

Carrier

The carrier shell is simply a hollow carrier equipped with a fuze which ejects the contents at a calculated time. They are often filled with propaganda
Propaganda
Propaganda is a form of communication that is aimed at influencing the attitude of a community toward some cause or position so as to benefit oneself or one's group....

 leaflets (see external links), but can be filled with anything that meets the weight restrictions and is able to withstand the shock of firing. Famously, on Christmas Day 1899 during the siege of Ladysmith
Siege of Ladysmith
The Siege of Ladysmith was a protracted engagement in the Second Boer War, taking place between 30 October 1899 and 28 February 1900 at Ladysmith, Natal.-Background:...

, the Boer
Afrikaner
Afrikaners are an ethnic group in Southern Africa descended from almost equal numbers of Dutch, French and German settlers whose native tongue is Afrikaans: a Germanic language which derives primarily from 17th century Dutch, and a variety of other languages.-Related ethno-linguistic groups:The...

s fired into Ladysmith a carrier shell without fuze, which contained a Christmas pudding
Christmas pudding
Christmas pudding is a pudding traditionally served on Christmas Day . It has its origins in medieval England, and is sometimes known as plum pudding or plum duff, though this can also refer to other kinds of boiled pudding involving dried fruit.-Basics:Many households have their own recipe for...

, two Union Flag
Union Flag
The Union Flag, also known as the Union Jack, is the flag of the United Kingdom. It retains an official or semi-official status in some Commonwealth Realms; for example, it is known as the Royal Union Flag in Canada. It is also used as an official flag in some of the smaller British overseas...

s and the message "compliments of the season". The shell is still kept in the museum at Ladysmith.

Fireworks

Aerial firework bursts are created by shells. In the United States, consumer firework shells may not exceed 1.75 inches in diameter.

Unexploded shells

The fuze
Artillery fuze
An artillery fuze or artillery fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns , howitzers and mortars. A fuze is a device that initiates an explosive function in a munition, most commonly causing it to detonate or release its contents, when its...

 of a shell has to keep the shell safe from accidental functioning during storage, due to (possibly) rough handling, fire, etc., it also has to survive the violent launch through the barrel, then reliably function at the correct time. To do this it has a number of arming mechanisms, which are successively enabled under the influence of the firing sequence.

Sometimes, one or more of these arming mechanisms fails, and if the fuze is installed on an HE shell, it fails to detonate on impact. More worrying and potentially far more hazardous are fully armed shells on which the fuze fails to initiate the HE firing. This may be due to shallow, low velocity or soft impact conditions. Whatever the reason for failure, such a shell is called a blind or unexploded ordnance (UXO). The older term, "dud", is discouraged because it implies that the shell cannot detonate. Blind shells often litter old battlefields and depending on the impact velocity may be buried some distance into the earth, all remain potentially hazardous. For example, antitank ammunition with a piezoelectric fuze can be detonated by relatively light impact to the piezoelectric element, and others, depending on the type of fuze used can be detonated by even a small movement. The battlefields of the First World War still claim casualties today from leftover munitions. Modern electrical and mechanical fuzes are highly reliable: if they do not arm correctly they keep the initiation train out of line, or if electrical in nature, discharge any stored electrical energy.

Guided shells

Guided or "smart" ammunition have been developed in recent years, but have yet to supplant unguided munitions in all applications.

Range enhancing technologies

Shells may be modified into Rocket Assisted Projectile
Rocket Assisted Projectile
A Rocket Assisted Projectile is an artillery or cannon round incorporating a rocket motor for independent propulsion. This grants the projectile both greater speed and range than an ordinary shell, which is propelled only by the ballistic force of the gun's exploding charge...

s (RAP) and base bleed
Base bleed
Base bleed is a system used on some artillery shells to increase their range, typically by about 30%.Most of the drag on an artillery shell comes from the nose of the shell, as it pushes the air out of its way at supersonic speeds. Shaping the shell properly can reduce this greatly. However,...

rounds to increase range.

External links

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