M67 recoilless rifle

The M67 recoilless rifle was a 90-mm antitank recoilless rifle made in the United States and later in the Republic of Korea. It could also be employed in an antipersonnel role with the use of the M590 antipersonnel round. It was designed to be fired primarily from the ground using the bipod and monopod, but it could also be fired from the shoulder using the folded bipod as a shoulder rest and the monopod as a front grip. The weapon was air-cooled and breech-loaded, and fired fixed ammunition. It is a direct fire weapon employing stadia lines to allow simple range finding, based on a typical tank target bridging the lines once in range.

History and use
Introduced in the early 1960s in Army and Marine Corps service, the M67 was used in the Vietnam War together with the much larger 106mm M40. The M67 proved a reliable and effective weapon, though it was primarily used against personnel and fortifications in combat, and saw little or no use against armor. While troops praised its effectiveness, the M67 came in for heavy criticism due to the weapon's weight and length as well as its backblast, which often precluded its use in offensive operations. Because of these disadvantages, some Marine Corps units continued to use the old M20 rocket launcher (Super Bazooka) in preference to the M67. It was largely replaced in Army service by the TOW missile system in 1970 and the M47 Dragon anti-tank missile system in 1975.

The M67 was not completely withdrawn from infantry service. Instead, it was retained as a substitute standard antitank weapon for special tasks or battle environments. Since the batteries of the Dragon and the wires of the TOW could fail due to extremely low temperatures, the M67 was used for units deploying to arctic environments and remained in many infantry units in West Germany, such as the 1st Battalion, 15th Infantry, 3rd Infantry Division. As of 1988, the 6th Light Infantry Division in Alaska was still using the M67 in its special weapons platoons. Two M67s were used by C Co 5/87th (Lt Infantry) 193rd Infantry Brigade during Operation "Just Cause" in the Republic of Panama in 1989, using the M590 Antipersonal Ammunition. Similarly, the urban environment of West Berlin prompted the Army to keep the weapon with the 4th, 5th and 6th Battalions of the 502nd Infantry Regiment, Berlin Brigade as late as winter of 1991; the M47 Dragon replaced it in January 1992. The Army Rangers also retained the M67 in its weapons platoons until it was replaced by the 84mm M3 Carl Gustav in the 1990s. In addition to its role as an anti-tank weapon, the M67 was issued to Combat Engineer units as a demolition gun, intended to destroy bunkers and other hard point targets. Combat Engineer units had the M67 as part of their MTOE (Modified Table Of Organization & Equipment) at least as late as 1990.

In February 2011, it was reported that stocks of surplus M67 recoilless rifles were reintroduced to the 101st Airborne Division for limited combat service in Afghanistan. Numbers of these weapons were issued to the 506th Infantry Regiment, "Currahee", 4th Brigade Combat Team, for use against fortifications, and concentrations of enemy personnel. The M67 was issued in response to a demand for a reloadable shoulder-fired weapon to be used in static defensive positions as well as ambushes. In particular, the flechette antipersonnel round is seeing common usage.

Description
The M67 is shaped like a long tube with the sight assembly and trigger offset to the side in opposite directions about halfway along the barrel. Under this point is the monopod, with the bipod halfway back from there. The weapon required a crew of three to operate it; a gunner, assistant gunner (loader) and ammo bearer. The breech is hinged on the right side, and had to be swung open to load the round. It was then swung closed and when the rifle was fired, the rear end of the shell case broke up and was blown out of the back of the breech block. On the left side of the barrel, near the sight and trigger assemblies, was an asbestos heat shield to protect the gunner's shoulder and neck from the heat of the barrel when firing.

It was capable of maintaining a sustained fire rate of 1 round per minute, but the weapon could also be rapid fired at an increased rate of 1 round every 6 seconds (10 rpm) by a well trained crew. The rapid firing was limited to 5 rounds, with a mandatory 15 minute cool-off period afterward.

The M49A1 sub-caliber device, which uses NATO 7.62-mm rounds, is typically used for zeroing the sight and for qualifying purposes. The sight would be visually zeroed by setting crossed strings over the gun barrel opening (there was a rubber loop and notches at the end of the barrel to facilitate holding the string in the correct position), then looking through the barrel of the sub-caliber device (and crossed strings) and setting the fixed stadia, reticle sight to the same target. The sub-caliber rounds could then be used to further refine the zero and to qualify.

Ammunition
Ammunition for the 90 mm rifle was issued in complete fixed cartridges. The term "fixed" means that the projectile and the cartridge case are crimped together. This ensures correct alignment of the projectile and the cartridge case. It also permits faster loading because the projectile and the cartridge case are loaded as one unit. The rear end of the cartridge case is made of frangible material that is completely destroyed when fired. The projectiles used are pre-engraved with a rifling band, that is, the rotating bands are cut to engage the rifled bore both to trap gases and to spin-stabilize the projectile.

M371 practice round
The M371 is a practice round for the M371A1 HEAT round. It has the high explosive filler replaced with inert ballast to keep it at the same weight and flight properties. The nose cap contains a smoke pellet to mark the point of impact.


 * Cartridge weight: 9.25 lb (4.2 kg)
 * Cartridge length: 28.10 in (714 mm)
 * Projectile weight: 6.75 lb (3.06 kg)
 * Muzzle velocity: 700 ft/s (213 m/s)
 * Maximum effective range: 437 yd (400 m)
 * Fuse: PIBD M530A1

M371A1 HEAT round
The M371A1 round utilizes a special fin-stabilized projectile which employs the shaped charge principle to defeat armor. It does not depend upon velocity at the moment of impact for its effect. It relies upon a concentration of the effect of the explosive filler through its shape. The conical shape of the filler concentrates the force of the explosion into a hot jet that blows its way through the armor. The shape of the filler is maintained by a metal cone which forms a slug when the filler is exploded. This slug or metal may or may not follow the explosive jet through the armor. The end of the projectile is a long and narrow stand-off of a length that allows the HEAT jet to achieve maximum effect against the target.

The HEAT round is used primarily against armor. It can also be used against secondary targets such as gun emplacements and pillboxes with excellent results. It is capable of penetrating 3.5 ft (1.1 m) of packed soil, 2.5 ft (0.8 m) of reinforced concrete, or 1.15 ft (350mm) of armor plate (steel).


 * Cartridge weight: 9.25 lb (4.2 kg)
 * Cartridge length: 28.10 in (714 mm)
 * Projectile weight: 6.75 lb (3.06 kg)
 * Muzzle velocity: 700 ft/s (213 m/s)
 * Maximum effective range: 437 yd (400 m)
 * Fuse: PIBD M530A1

M590 Antipersonnel Canister
The Antipersonnel (Canister) Cartridge M590 (XM590E1) or M590 cartridge is a flechette round designed for close-in defense against massed attacks on personnel positions. The cartridge consists of an aluminum cartridge case crimped to an aluminum canister. The canister consists of a thin-walled, deep-drawn, scored aluminum body which contains a payload of 2400 eight-grain (0.5 g), low-drag, fin-stabilized, steel-wire flechettes. The sides are scored to facilitate splitting when the round is fired.

When the projectile leaves the muzzle, the pressure ruptures the canister along the score marks to release the flechettes which disperse in a cone angle of approximately 8 degrees.


 * Cartridge weight: 6.79 lb (3.08 kg)
 * Cartridge length: 19.19 in (487 mm)
 * Projectile weight: 3.97 lb (1.8 kg)
 * Muzzle velocity: 1,250 ft/s (381 m/s)
 * Maximum effective range: 328 yd (300 m)
 * Fuse: none

Performance relative to comparable weapons
Data is from Jane's Infantry Weapons 1984–85

References and notes

 * (JIW) Hogg, Ian. Jane's Infantry Weapons 1984–85, London: Jane's Publishing Company Ltd., 1984.