The 8 inch (203 mm) M110 self-propelled howitzer is an American-made self-propelled artillery system consisting of an M115 203 mm howitzer installed on a purpose-built chassis. Before its retirement from US service, it was the largest available self-propelled howitzer in the United States Army's inventory; it continues in service with the armed forces of other countries, to which it was exported. Missions include general support, counter-battery fire, and suppression of enemy air defense systems. Description According to the operator's manual, the M110's typical rate of fire was three rounds per two minutes when operated at maximum speed, and one round per two minutes with sustained fire. The M110 featured a hydraulically operated rammer to automatically chamber the 200+ pound projectile. These rammers were prone to breakdown and generally slowed operation of the gun because the rammers required crews to completely lower the massive barrel before using it. Well trained and motivated crews could achieve two to four rounds per minute for short periods by using the manual rammer, essentially a heavy steel pole with a hard rubber pad on one end. Using the manual rammer was physically demanding, but crews were not required to lower the barrels as much as with the hydraulic rammer. The M110's range varied from to approximately when firing standard projectiles, and up to when firing rocket-assisted projectiles. History The M110 howitzer first entered service with the U.S. Army in 1963 and was used in the Vietnam War by the United States Army. Later versions were used in the Gulf War - Operation Desert Shield and Operation Desert Storm by Tango Battery 5th Battalion 11th Marines, and the British Army's 32nd Regiment Royal Artillery. In 1977 the upgraded M110A1 entered service, featuring a longer M201 series barrel which gave an increased range. The M110A2 is the latest version with a double muzzle brake, in contrast to the earlier A1 version which had a plain muzzle. The 2nd Battalion 18th Field Artillery (U.S. Army) which deactivated in 1994 at Fort Sill, Oklahoma, and the 5th Battalion 18th Field Artillery served in Desert Storm with the M110A2 Howitzer, as well as the 142nd Field Artillery Brigade (Arkansas Army National Guard), and 1st BN 181 Field Artillery (Tennessee Army National Guard). Most of the U.S. Army and USMC relied on the M109 series 155-millimeter howitzer gun systems during this conflict; sending remaining M110s to reserve or National Guard units.