M67 90mm Recoilless Rifle
The M67 90mm recoilless rifle is a breech-loaded, singleshot, man-portable, crew-served weapon. It can be used in both anti-tank and anti-personnel roles. It can be fired it from the ground, using the bipod or the monopod, or from the shoulder. The most stable firing position is the prone position. The weapon is air-cooled and fires fixed ammunition. The rifle is equipped with a manually operated breech mechanism and a percussion-type firing mechanism. It is designed for direct firing only, and sighting equipment for this purpose is furnished with each weapon.
The M67 recoilless rifle is classified as a flat trajectory weapon. The muzzle velocity and the weight of the projectile are the more important factors in determining the flatness of the trajectory. In all cases, however, due to the action of the force of gravity and air resistance, the trajectory of projectiles is actually a curve and not a straight line. Air resistance retards the projectile during its flight, causing the angle of fall to be greater than the angle of elevation. Therefore, the projectile reaches its maximum ordinate (highest point) closer to the point of impact than to the rifle.
Studies in the 1940s had exposed a US Army requirement for a 90mm recoilless rifle. The US Army Ordnance Corps subsequently awarded a contract to Arthur D. Little, Inc. to develop a 90mm design. The weapons were to be developed as part of a Platoon Anti-Tank Weapon program (abbreviated as PAT). The desired weapon would be less than 30 pounds, capable of being fired from the ground or shoulder, accurate to 500 yards, and capable of defeating 6 inches of armor at a maximum obliquity of 60 degrees.
The weapon developed by Arthur D. Little in the late 1940s and early 1950s was designated as the T149. The T149 differed from other contemporary recoilless designs in having a 2-lobe nozzle breech that effectively formed a cam ring. The weapon also featured a firing pin that drove radially into a side-fire percussion cap in the cartridge base. The Arthur D. Little design was complemented by the development of fin-stabilized projectiles specifically for the new weapon.
In December 1951, Midwest Research Institute (MRI) was awarded a contract to develop a competing 90mm design, later designated as the T184. A change in the requirements for the PAT led to the Office of the Chief of Ordnance setting priorities on the development of the system in February 1952. The T149 design was given the lowest priority as a result. With its development effectively halted, the T149 and its ammunition were never presented for user tests. The focus shifted to the T184.
The T184 achieved its low weight design, a continued requirement for the PAT, but using ammunition with a reverse tapered cartridge case, allowing the use of a smaller, lighter breech block. The breech block itself consisted of a 2-part assembly making use of a lightweight aluminum venturi expansion cone. Though the weapon met the weight requirements, having a bear weight of 25 pounds, it could not achieve the desired accuracy and first round hit probability. Rocket assisted ammunition was developed in an attempt to help stabilize the flight path, velocity, and overall accuracy of the projectile. The redesigned ammunition was then found to be unable to meet the penetration requirements.
In 1955, further development of the T184 was terminated. MRI was contracted to develop a follow-on design to meet revised PAT requirements. The revised requirements included a weapon weight of up to 30 pounds. This was hoped to allow for the construction of a stronger chamber that would allow greater maximum pressures and obviate the need for the rocket-assisted ammunition. The T219 eventually came to use the ammunition that had been under development at Arthur D. Little for the T149.
The final developmental design, the T219E4, weighed 35 pounds with equipment. The weapon was type classified in August 1959 as the M67 and referred to commonly at that time as the Medium Anti-Tank Weapon (MAW). The type classification was done despite reservations on the weapon's cold-weather performance, with the understanding that fixes for the issues would be developed and integrated into the issue weapons. A spotting pistol was also developed for the M67, designated the XM14, but was not standardized or issued.
The weapon was subsequently issued at platoon level in the US Army being found in the platoon's weapon squad in most types of infantry units. There it replaced the M20A1B1 3.5" rocket launcher. The weapon was in front line service into the 1970s, until it began to be replaced by the M47 Dragon missile system. Ironically, despite its initial cold-weather issues, similar issues with the Dragon missile led to the continued issue to various units. The M67 remained in inventory as a substitute standard weapon into the 1980s and in active service with the 75th Ranger Regiment into the 1980s. It was also used by the US Air Force as part of the weapons available to Security Police/Security Forces personnel.
The M47 Dragon and residual M67s were finally replaced in front line units with the Javelin missile system in the 1990s. The 75th Ranger Regiment adopted the commercially available Carl Gustav M3 recoilless rifle as a replacement in 1990 (known first as the Ranger Anti-Armor/Anti-Personnel Weapon System or RAAWS, before being retitled the Multi-Role Anti-Armor/Anti-Personnel Weapon System or MAAWS).
In February 2011, it was reported that soldiers assigned to the 4th Brigade Combat Team, 101st Airborne Division in Afghanistan's Paktika Province had been reissued M67 recoilless rifles. The stated plan was to use the weapon to defend static positions. It was also a cost-effective alternative to other systems, such as the Javelin missile, and featured a wider range of ammunition types. The unit also expected to explore using the weapon offensively.
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