The M110 155 mm projectile is an

artillery shell A shell, in a modern military context, is a projectile whose payload contains an explosive, incendiary device, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military ...

used by the

U.S. Army The United States Army (USA) is the primary land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United Stat ...

and

U.S. Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines or simply the Marines, is the maritime land force service branch of the United States Department of Defense. It is responsible for conducting expeditionary ...

. The M110 was originally designed as a

chemical A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...

artillery round to deliver

blister agent A blister agent (or vesicant) is a chemical compound that causes severe skin, eye and mucosal pain and irritation in the form of severe chemical burns resulting in fluid filled blisters. Named for their ability to cause vesication, blister a ...

s via howitzer as a replacement for the World War I-era 75 mm chemical projectiles. The design was later repurposed as a

white phosphorus White phosphorus, yellow phosphorus, or simply tetraphosphorus (P4) is an allotrope of phosphorus. It is a translucent waxy solid that quickly yellows in light (due to its photochemical conversion into red phosphorus), and impure white phospho ...

smoke round for marking, signaling, and screening purposes. The white phosphorus variants of the shell also have a secondary, incendiary effect.

Original design

Officially designated ''projectile, 155 mm howitzer, M110'', the original round was a 26.8-inch (68.1 cm) steel shell with a rotating band near its base and a burster rod down its center. The original shell typically contained of sulfur mustard (H) or distilled sulfur mustard (HD), which would fill the hollow space in the shell. As early as the 1960s, a

version was created under the same designation with of white phosphorus filler. Both versions were designed for employment by the M114 howitzer and the M44 Self-Propelled Howitzer for use as terrain denial (in the case of the mustard-filled versions), target-marking, and obscuration (in the case of the white phosphorus versions.)

Design variants and markings

M110

The original version of the shell came in two variations, one filled with mustard (HD) (projectile, gas, persistent, HD, 155 mm howitzer, M110) and one filled with white phosphorus (WP) (projectile, smoke, WP, 155 mm gun, M110). To distinguish between the two, the HD versions were gray marked with two, horizontal, green bands, like most other

artillery shells. The WP versions were gray with a single, horizontal, yellow band, as is standard for military smoke munitions. Both versions are now considered obsolete, with the WP version seeing updated versions in later incarnations of the shell. The HD version has not been produced since the 1960s and was never used in combat. Remaining stockpiles of the HD version are in the process of being destroyed in accordance with the 1997 Chemical Weapons Convention.

M110A1

The first upgrade to the M110 shell is only slightly modified from the original, maintaining the white phosphorus filler weight of the original with slight modifications to the release mechanisms to make the shell more reliable. It is primarily used for

signaling A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. ...

and small-scale screening missions. The M110A1 is gray with a single, yellow, horizontal band, which is standard for military smoke munitions.

M110A2

The second upgrade to the M110 shell is more dramatically modified from the other two variants, with thinner casing to increase the amount of filler that can be placed in the shell. The M110A2 contains of white phosphorus, which increases the duration of the smoke it produces. This change makes the M110A2 ideal for target marking and large-scale obscuration missions. The M110A2 is gray with a single, yellow, horizontal band, which is standard for military smoke munitions.

Similar projectiles

M104 155 mm projectile The M104 155 mm projectile is a chemical artillery shell designed for use by the U.S. Army. It was specifically designed to carry about of sulfur mustard (H) or (HD) blister agent (distilled mustard). As early as the 1960s, the shell was also fi ...

M121 155 mm projectile The M121/A1 155 mm projectile was a chemical artillery shell designed for use by the U.S. Army. It was designed to be used with approximately of GB or VX nerve agents. History The U.S. Army standardized the M121 shell in 1954 as an artillery sh ...

M687 155 mm projectile The M687 was an American 155 mm binary sarin chemical artillery shell. The design was standardized in 1976 and production began on December 16, 1987 at Pine Bluff Arsenal, Pine Bluff, Arkansas. Production was halted three years later, following t ...

References

{{U.S. chemical weapons 155 mm artillery shells Chemical weapon delivery systems Chemical weapons of the United States