The M110 155mm Projectile is an

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

used by the U.S. Army and

U.S. Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through comb ...

. The M110 was originally designed as a chemical 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. They are named for their ability to cause severe chemical burns, resulting in painful water blisters on the bodies of those affe ...

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

white phosphorus Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids. Solid violet and black allotropes are also known. Gaseous phosphorus exists as diphosphorus and atomic phosphorus. White phosphorus White ...

smoke round for marking, signaling, and screening purposes. The

variants of the shell also have a secondary, incendiary effect.

Original design

Officially designated Projectile, 155mm 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 The M44 was an American-made self-propelled 155 mm howitzer based on the M41 Walker Bulldog tank chassis, first introduced in the early 1950s. Flaws in its design prevented it from seeing action in the Korean War, but the type went on to serve i ...

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, 155mm Howitzer, M110) and one filled with white phosphorus (WP) (Projectile, Smoke, WP, 155mm Gun, M110). To distinguish between the two, the HD versions were gray marked with two, horizontal, green bands, like most other chemical 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

filler weight of the original with slight modifications to the release mechanisms to make the shell more reliable. It is primarily used for

signaling In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...

and small-scale

screening Screening may refer to: * Screening cultures, a type a medical test that is done to find an infection * Screening (economics), a strategy of combating adverse selection (includes sorting resumes to select employees) * Screening (environmental), a ...

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

, 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 155mm 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 155mm Projectile The M121/A1 155mm 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 she ...

* M687 155 mm Projectile

References

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