Shell (projectile)

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This article is about the artillery projectile. For the small arms cartridge, see shotgun shell.
Some sectioned shells from the First World War. From left to right: 90 mm fragmentation shell, 120 mm pig iron incendiary shell, 77/14 model - 75 mm high explosive shell, model 16–75 mm fragmentation shell
Some shells displayed in Taipei

A shell is a payload-carrying projectile which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes[citation needed] large solid projectiles properly termed shot (AP, APCR, APCNR, APDS, APFSDS and proof shot). Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used. Originally it was called a "bombshell", but "shell" has come to be unambiguous in a military context. "Bombshell" is still used figuratively to refer to a shockingly unexpected happening or revelation.


Shells are usually large-calibre projectiles fired by artillery and combat vehicles (including tanks), and warships.



Solid cannonballs (“shot”) did not need a fuse, but hollow munitions (“shells”) filled with something such as gunpowder to fragment the ball, needed a fuse, either impact (percussion) or time. Percussion fuses 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 fuse that was ignited before or during firing and burnt until the shell reached its target.

Early shells[edit]

The 'flying-cloud thunderclap-eruptor' cannon from the Huolongjing.


Written evidence for early explosive shells in China appears in the early Ming Dynasty (1368–1644) Chinese military manual Huolongjing, compiled by Jiao Yu (fl. 14th to early 15th century) and Liu Ji (1311–1375) sometime before the latter's death, a preface added by Jiao in 1412.[3] As described in their book, these hollow, gunpowder-packed shells were made of cast iron.[3]

An early problem was that there was no means of measuring the time precisely enough — reliable fuses did not yet exist and the burning time of the powder fuse was subject to considerable trial and error. Early powder burning fuses had to be loaded fuse down to be ignited by firing or a portfire put down the barrel to light the fuse. Other shells were wrapped in bitumen cloth which would ignite during the firing and in turn ignite a powder fuse. Nevertheless, shells came into regular use in the 16th Century, for example a 1543 English mortar shell was filled with 'wildfire'.

A mortar with a hollowed shell from the Boshin war.

By the 18th Century it was known that the fuse towards the muzzle could be lit by the flash through the windage between shell and barrel. At about this time 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.

The use of exploding shells from field artillery became relatively commonplace from early in the 19th Century. Until the mid 19th century, shells remained as simple exploding spheres that used gunpowder, set off by a slow burning fuse. They were usually made of cast iron, but bronze, lead, brass and even glass shell casings were experimented with.[4] The word bomb encompassed them at the time, as heard in the lyrics of The Star-Spangled Banner ("the bombs bursting in air"), although today that sense of bomb is obsolete. 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 fuses 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.[5] The sabot was also intended to reduce jamming during loading. Despite the use of exploding shell, the use of smoothbore cannons, firing spherical projectiles of shot, remained the dominant artillery method until the 1850s.

Shrapnel shell[edit]








Modern shell[edit]

The mid 19th century saw a revolution in artillery, with the introduction of the first practical rifled breach loading weapons. The new methods resulted in the reshaping of the cylindrical shell into its modern recognizable cylindro-conoidal form. This shape greatly improved the in-flight stability of the projectile and meant that the primitive time fuzes could be replaced with the percussion fuze situated in the nose of the shell. The new shape also meant that further, armour piercing designs could be used.

Rifled breach loaders[edit]

Main article: Rifled breech loader




Rifled guns were also developed elsewhere - by Major Giovanni Cavalli and Baron Martin von Wahrendorff in Sweden, Krupp in Germany and the Wiard gun in the United States.[12] However, rifled barrels required some means of engaging the shell with the rifling. Lead coated shells were used with the Armstrong gun, 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 also tried without success.


Percussion fuze[edit]


The percussion fuze was adopted by Britain in 1842, many designs were jointly examined by the army and navy, but were unsatisfactory, probably because of the safety & arming features. However, in 1846 the design by Quartermaster Freeburn of the Royal Artillery was adopted by the army. It was a wooden fuze some 6 inches long and used shear wire to hold blocks between the fuze magazine and a burning match. The match was ignited by propellant flash and the shear wire broke on impact. A British naval percussion fuze, made of metal did not appear until 1861.[14]

Smokeless powders[edit]

Poudre B was the first practical smokeless powder.



Sir James Dewar developed the cordite explosive in 1889.

In 1884, Paul Vieille invented a smokeless powder called Poudre B (short for poudre blanche—white powder, as distinguished from black powder)[17] made from 68.2% insoluble nitrocellulose, 29.8% soluble nitrocellusose gelatinized with ether and 2% paraffin. This was adopted for the Lebel rifle.[18] Vieille's powder revolutionized the effectiveness of small guns, because it gave off almost no smoke and was three times more powerful than black powder. Higher muzzle velocity meant a flatter trajectory and less wind drift and bullet drop, making 1000 meter shots practicable. Other European countries swiftly followed and started using their own versions of Poudre B, the first being Germany and Austria which introduced new weapons in 1888. Subsequently Poudre B was modified several times with various compounds being added and removed. Krupp began adding diphenylamine as a stabilizer in 1888.[16]


High explosive shells[edit]

Picric acid was used in the first high explosive shells. Cut out section of a high explosive shell belonging to a Canon de 75 modèle 1897.



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 the recognition that far smaller fragments than hitherto would give a better effect. This guideline was achieved by the 1960s with the 155mm L15 shell, developed as part of the German-British FH-70 program. The key requirement for increasing the HE content without increasing shell weight was to reduce the thickness of shell walls, which required improvements in high tensile steel.

Armour piercing shells[edit]


Britain also deployed Palliser shells in the 1870s-1880s. In the shell the cavity was slightly larger than in the shot and was filled with gunpowder instead of being empty, to provide a small explosive effect after penetrating armour plating. The shell was correspondingly slightly longer than the shot to compensate for the lighter cavity. The powder filling was ignited by the shock of impact and hence did not require a fuze.[7]



A shell with sabot in an 1824 Paixhans gun.


A diagram of a fin stabilized discarding sabot showing its operation.




In contrast, 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. Although a full range of shells and shot could be used, changing the adaptor in the heat of battle was highly impractical.

Anti tank explosive shells[edit]
Diagram of PIAT ammunition



Claims for priority of invention are difficult to resolve due to subsequent historic interpretations, secrecy, espionage, and international commercial interest.[27] By mid-1940 Germany introduced the first HEAT round to be fired by a gun, the 7.5 cm fired by the Kw.K.37 L/24 of the Panzer IV tank and the Stug III self-propelled gun (7.5 cm Gr.38 Hl/A, later editions B and C). In mid-1941 Germany started the production of HEAT rifle-grenades, first issued to paratroopers and by 1942 to the regular army units. In 1943 the Püppchen, Panzerschreck and Panzerfaust were introduced. The Panzerfaust and Panzerschreck or 'tank terror' gave the German infantryman the ability to destroy any tank on the battlefield from 50-150m with relative ease of use and training (unlike the UK PIAT).

The first British HEAT weapon to be developed and issue was a rifle grenade using a 2 1/2 inch cup launcher on the end of the barrel; the British No. 68 AT grenade issued to the British army in 1940. By 1943 the PIAT was developed; a combination of a HEAT warhead and a spigot mortar delivery system. While cumbersome the weapon at last allowed British infantry to engage armour at range; the earlier magnetic hand-mines and grenades required them to approach suicidally close.[28] During World War II the British referred to the Monroe effect as the cavity effect on explosives.[29]



105 mm HESH rounds being prepared for disposal by the US Navy, 2011.



Other shell types[edit]

Drawing of a carcass shell.

A variety of fillings have been used in shells throughout history. An incendiary shell was invented by Valturio in 1460. The carcass shell was first used by the French under Louis XIV in 1672.[30] Initially in the shape of an oblong in an iron frame (with poor ballistic properties) it evolved into a spherical shell. Their use continued well into the 19th Century.

A modern version of the incendiary shell was developed in 1857 by the British and was known as Martin's shell. It was filled with molten iron and was used against enemy warships. It replaced the use of red hot shot (notably used at the Great Siege of Gibraltar in 1782). Two patterns of incendiary shell were used by the British in World War 1, one designed for use against Zeppelins.[31]

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 512 inch calibres. The 10-inch wasn't officially declared obsolete until 1920.[32]

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.[32]



British gun crew preparing 155mm shells at Vergato, Italy on 22 February 1945


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 guns, Gustav and Dora, which were 800 mm (31.5") in calibre. Very large shells have been replaced by rockets, guided missile, and bombs, and today the largest shells in common use are 155 mm (6.1").


155mm American artillery shells, March 1945

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 supergun fired 4.8 and 7.1 tonne shells.

During the 19th Century the British adopted a particular form of designating artillery. Field guns were designated by nominal standard projectile weight while howitzers were designated by barrel caliber. British guns and their ammunition were designated in pounds, 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. A mixture of designations were in use for land artillery from the First World War (such as the 60-pounder gun, 2.5 inch mountain gun, 4 inch gun, 4.5 inch howitzer) through to the end of World War II (5.5 inch medium gun, 25-pounder gun-howitzer, 17-pounder tank gun) but the majority of naval guns were by caliber. After World War II, guns were designated by calibre.



High-explosive [edit]

15 inch high-explosive howitzer shells. Circa 1917.

The most common shell type is high explosive, commonly referred to simply as HE. They have a strong steel case, a bursting charge, and a fuse. The fuse 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 used to describe the shell pieces, but shrapnel shells functioned very differently and are long obsolete. Depending on the type of fuse 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).



Mine shell[edit]



Armour-piercing [edit]



A further refinement of such designs improves penetration by adding a softer metal cap to the penetrating nose giving armour-piercing, capped (APC) design. The softer cap damps 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: Armour-piercing, capped, ballistic cap (APCBC).[33]

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 [edit]

The armour-piercing concept calls for more penetration capability than the target's armour thickness. Generally, the penetration capability of an armor piercing round increases with the projectile's kinetic energy and also with concentration of that energy in a small area. 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, or otherwise disintegrate. At relatively high impact velocities, steel is no longer an adequate material for armor piercing rounds. 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, and to their high melting and boiling temperatures. They also have very high density. Energy is concentrated 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 and resulting kinetic energy.

Once outside the barrel, the sabot is stripped off by a combination of centrifugal force 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 [edit]

French "Arrow" armour-piercing round, a form of APFSDS


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 heavy alloys (WHA) or depleted uranium (DU); maraging steel 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 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.[citation needed]

Armour-piercing, composite rigid [edit]

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 surrounded by a full-bore shell of a lighter material (e.g., an aluminium 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 concept of a heavy, small-diameter penetrator encased in light metal would be later employed in small-arms armor-piercing incendiary and HEIAP rounds.

Armour-piercing, composite non-rigid [edit]

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 or a final added section. 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.[25]

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

High-explosive, anti-tank [edit]

HEAT shells are a type of shaped charge used to defeat armoured vehicles. They are extremely efficient at defeating plain steel armour but less so against later composite and reactive armour. 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 bomb. HEAT shells are less effective if spun (i.e., fired from a rifled gun).




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

Shrapnel shells[edit]

Main article: Shrapnel shell
Typical World War I shrapnel round :
1 shell bursting charge
2 bullets
3 nose fuze
4 central ignition tube
5 resin matrix
6 thin steel shell wall
7 cartridge case
8 propellant



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 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[edit]


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.




155 mm artillery shells containing "HD" agent at Pueblo chemical weapons storage facility. Note the colour-coding scheme on each shell.


Non-lethal shells[edit]




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 rounds fired from a M777 howitzer






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

Proof shot[edit]

Main article: Proof test


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.

Unexploded shells[edit]

Main article: Unexploded ordnance
Modern 155mm artillery ammunition



Guided shells[edit]


Range enhancing technologies [edit]


See also[edit]


  2. ^ Hogg pg 164
  4. ^ Hogg pg 164 - 165
  5. ^ Hogg pg 165
  6. ^ Marshall, 1920.
  9. ^ Marshall J. Bastable. "From Breechloaders to Monster Guns: Sir William Armstrong and the Invention of Modern Artillery, 1854-1880". JSTOR. Retrieved November 19, 2013. 
  10. ^ "William Armstrong". 
  11. ^ "The Emergence of Modern War". 
  12. ^ Hogg pg 80 - 83
  13. ^ a b Hogg pg 165 - 166
  14. ^ Hogg pg 203 - 203
  22. ^ "The Amazing Huascar"
  31. ^ Hogg pg 171 - 174
  32. ^ a b Hogg pg 174 - 176
  34. ^ I.V. Hogg & L.F. Thurston, "British Artillery Weapons & Ammunition". London: Ian Allan, 1972. Page 215.


External links[edit]