During World War II, the basic weapons of the U.S. infantryman were the rifle, light machine gun and fragmentation grenades. Hand and rifle grenades were used for short-range area targets. Hand-thrown grenades have a realistic range of 30 to 50 yards. The maximum range of rifle-launched grenades was approximately 100 yards; both were ill-suited for engaging targets with accurate indirect fire. Light mortars were used for ranges from 300 to 900 yards. The same weapons and limitations were fielded during the Korean Conflict by U.S. infantryman.

The Rifle Grenade Launcher

During the late 1950s, the M7A3 grenade launcher adapter was being issued for use on the M1 rifle. After the M14 rifle replaced the M1, the M76 grenade launcher was adopted. For accuracy, the M15 tilting-bar sight, designed to be attached to the M14 rifle’s stock, was issued for use with the M76 launcher. Special “grenade launching cartridges” were used. Rifle grenades could also be launched from the M16 rifle, but no special adapter was needed; grenades could be slipped over the NATO standard 22mm diameter flash suppressor. Disadvantages of launching grenades from rifle barrels included: short range, inaccuracy and heavy recoil that would sometimes break buttstocks.

Clearly, a new weapon was needed, one that could provide accurate direct and indirect fire to fill the gap between the rifle, hand grenades and the light mortar. During the 1950s the United States Ordnance Department began development of a weapon that could fire high explosive munitions, multiple projectile anti-personnel rounds and smoke and illumination rounds.

40mm Ammunition

During the early 1950s the Ballistic Research Laboratories at the Aberdeen Proving Ground developed a 40mm high-explosive, fragmentation projectile. The goal was a range of 400 meters at the relatively low velocity of 250 feet per second, with a recoil force no more than that of a 12-gauge shotgun. The new projectile used a high-low pressure system, which was developed by the German firm of Rheinmetall-Borsig during World War II for their 8cm 8H63 anti-tank gun. The advantage of the high-low system was that a lightweight barrel could be used, reducing the overall weight of the weapon.

The M79 Grenade Launcher

The concept of a lightweight weapon capable of projecting a grenade further than could be thrown by hand and could exceed the range of rifle-launched grenades was coordinated by the Small Arms Development Branch, headed by Colonel Studler. Jack Bird, a deputy to Colonel Studler, took an interest in the project; he built a crude launcher and brought it to the Pentagon to demonstrate. The device was comprised of a short length of tubing with the same inside diameter as a golf ball. To operate the “launcher,” a golf ball would be placed inside the tube and compressed against a spring. The golf ball was secured in place with a nail. Upon removing the nail, the golf ball would be launched. Bird, an avid golfer, suggested the name “Project Niblick” after the number nine iron, a high lofting golf club.

During 1953, the Project Niblick grenade launcher was under development at the Springfield Armory under the guidance of Cy Moore, with Dave Katz, a design engineer. The Picatinny Arsenal provided 40mm practice grenades for firing in the prototype launchers. There were three types of launchers being developed: a crude shoulder fired test fixture, a pistol and a three-shot semiautomatic launcher. The fixture was primarily a means of testing the ammunition to get an idea of the range and accuracy. The weight of the projectile was approximately 5.3 ounces. When launched with a quadrant elevation of 35 degrees, it had a range of 400 meters. Development commenced at the Springfield Armory. Proposed designs were identified by a letter “S” representing the Springfield Armory. Many of the designs never made it any further than the drawing board.

The Infantry Board at Fort Benning stated that they preferred a three-shot grenade launcher. A barrel length of 14 inches evolved as the length to make it unlikely that the gunner could get his fingers in front of the muzzle while firing. The three-shot launcher achieved semiautomatic operation through the use of a clip made up of three side-by-side chambers, each long enough to house a cartridge about 3.5 inches long. The clips would move to the left after firing by a constant force of a negator spring. As each round was fired, a latch detected the launching of the projectile and allowed the clip to move over until stopped by the next projectile, lining up that cartridge with the barrel. Although the basic concept was simple, the mechanism proved to be complex and unreliable. Continued misalignment between the projectile on the bore created gas leakage and a loss of accuracy. Special purpose rounds, such as CS gas or signal flares with a longer overall length, could not be used. The simplest design, designated as the “S-5,” was a single-shot, break-open type weapon. The S-5 evolved into the XM79 in 1959 after the three-shot S-6, T148E1 project was canceled.

After the idea of a multi-shot, semiautomatic launcher was scrapped, it was replaced by a simple, single-shot weapon, patterned after a break-open type shotgun. One launcher was ordered from Dave Mathewson, who operated a local fabrication shop, often used by the Springfield Armory. To keep the weight at a minimum, the weapon featured a hard-coated aluminum barrel. The odd shape of the stock was designed so that the bottom edge would be aligned with the line of recoil; the top or comb is contoured to keep the grenadier’s head upright owing to the line of sight relief when firing at low angles. To reduce the effects of the recoil on the shooter, a rubber recoil pad was fitted to the butt of the stock. The Infantry Board suggested a folding leaf sight mounted on the barrel with a bead front sight just above the muzzle. The XM79 launcher was sent to the Infantry Board in 1956 and was recommended for type classification in 1957.

To load the weapon, the operator simply moves the barrel-locking latch counter-clockwise to open the breech. Moving the release latch automatically puts the weapon into a safe position; opening the breech cocks the weapon. After closing the barrel, the safety must be pushed forward to fire. The weapon is easily field stripped by removing the front sling swivel screw and removing the forend. The barrel can then be disengaged from the fulcrum pin and separated from the receiver group.

The weight of the loaded launcher is 6.45 pounds; overall length is 28.78 inches. The stock and forearm are made of walnut. The rest of the weapon, except for the aluminum barrel, uses steel parts phosphated for corrosion protection. The original contract price for the M79 was $318.00 each. The M79 was issued with a small arms accessory case, which included a bore brush, plastic oil tube, combination tool and cleaning brush. Early carrying cases for the kit were made of canvas, later changed to vinyl.

During testing by the Infantry Board in June 1960, it was recommended that a new rear sight for the M79 launcher be designed and fabricated. The new sight was completed in October 1960. The early ladder-type sight was replaced with an adjustable, single crosspiece-type sight with a correction for azimuth. All launchers produced up to June 1960 had to be retrofitted. Confirmatory tests in December 1960 revealed requirements for additional windage adjustment on the rear sight. The additional sight modification was incorporated in the first production run. R&D continued in order to improve the reliability and function of the weapon. The launcher was considered acceptable by the Continental Army Command (CONARC) and was subsequently type-classified as the Launcher, Grenade, 40mm, M79 on December 15, 1960. By the first quarter of 1961, the new adjustable rear leaf sight was in full production, and several mandatory changes were implemented on the barrel locking lug, trigger spring and front sight.

The heat and humidity being experienced in Vietnam were causing problems with the warping and swelling of the wooden stocks of the M79. As a result, work began on designing a plastic buttstock and foregrip for the weapon. By 1964, a suitable plastic buttstock was available; General Tire was the primary contractor. There were no plastic foregrips adopted.

Although the M79 grenade launcher was designed and developed at the Springfield Armory, the majority were manufactured by civilian companies. Contracts awarded to private industry included: Action Manufacturing Company, Philadelphia, Pennsylvania, Contract DA-11-1199-ORD-736 and Exotic Metal Products, Pasadena, California, Contract DA-11-199-ORD-730. Other contracts were subsequently awarded to the Kanarr Corporation of Kingston, Pennsylvania, and Thompson Ramo Wooldridge (TRW) of Lyndhurst, Ohio. The decision to have private companies manufacture the M79, resulted in a lot of resentment with the civilian employees of the Springfield Armory. Series production ran from 1961 to 1971 with an estimated 350,000 M79 launchers produced.

Despite being replaced by modern grenade launchers, like the M320A1 and the M32A1, the M79 is still being fielded by the U.S. military.

The China Lake Grenade Launcher

Developed for the U.S. Navy SEAL teams was a limited production, pump-action 40mm grenade launcher, fed from an under-barrel tubular three-round magazine. The launcher was fitted with M79 front and rear sights and a shotgun-style stock. There was no official designation other than “The China Lake Grenade Launcher.” The weapon was developed at the Naval Weapons Center, China Lake, California, during 1967-1968.

The XM148 Grenade Launcher

While the adoption of the M79 grenade launcher solved one problem, it created another; it reduced the number of riflemen in a squad, the man carrying the single-shot M79 was usually armed with only a pistol for self-defense. To address the problem, the concept of the rifle-mounted launcher was studied. The 40mm XM148 launcher, first issued in 1967, was designed for mounting under the barrel of an M16 rifle. The weapon was developed by Colt Firearms to allow each rifleman in an infantry squad the ability to launch 40mm grenades, rather than one man equipped with an M79. During field testing in Vietnam, a number of problems were encountered. The XM148 launcher was not considered reliable or safe enough for type classification, and the launchers were pulled from service; most were destroyed.

The M203 Grenade Launcher

After the XM148 grenade launcher was scrapped, the concept of a rifle-mounted launcher was not. The Army initiated a competitive program for a new 40mm rifle-mounted grenade launcher. Designs were submitted by Aircraft Armaments Inc., Ford Aerospace and Communications Corporation and Aerojet Ordnance and Manufacturing Company. During August 1968, the Aircraft Armaments (AAI) design was type-classified as the XM203 grenade launcher. A small lot was manufactured and shipped to Vietnam for field testing. AAI’s XM203 40mm grenade launcher was found to be simple, safe and reliable. After successful testing and evaluation, the Aircraft Armaments design was type-classified as the Launcher, Grenade 40mm, M203 in 1969. Ironically, Aircraft Armaments, who developed the weapon, did not have the capacity to produce the number required by the Army, and a contract to manufacture the M203 was awarded to Colt Firearms. The U.S. M4 Carbine version of the M16 was adopted in 1994. The M203 launcher would not fit on the shorter M4. The M203 GL was modified into the M203A1, which is functionally the same as the M203 but is designed to fit on the M4 and M4A1 carbines. The quick-release M203A2 was designed for M4 carbines with a rail system and with M16A4 rifles that have the M5 adapter rail. Currently, there are at least seven U.S. companies manufacturing the M203 grenade launchers and its variants.

The M320 Grenade Launcher

During 2004, the U.S. Army issued a requirement for a new technically advanced grenade launcher with improved accuracy, ergonomics, safety and function as a stand-alone weapon. Development of the XM320 single-shot launcher, based on the HK AG36, began at the Picatinny Arsenal. The 40mm M320, which can also be attached under the barrel of a host weapon, was adopted in 2016 to replace the M203 under-barrel launcher.

The M32A1 Multi-Shot Grenade Launcher

While fighting in Iraq, the U.S. Marines requested a grenade launcher with a rapid rate of fire. An off-the-shelf, multi-shot revolver type, semiautomatic launcher was submitted by Milkor USA based in Arizona. The weapon was tested in 2006 and was eventually adopted by the U.S. Marine Corps as the M32A1 Multi-shot Grenade Launcher, and by the USSOCOM as the Mk 14 Mod 0.

Covert Ops Led to Experimental Smith & Wesson Model 76 Submachine Gun

During the 1961-1975 Vietnam War, the United States Navy had begun to procure submachine guns for use by its SEAL teams; a special operations force operating in-country. SEAL teams often used foreign submachine guns for their more covert operations for plausible deniability. Unhindered by any political, official standards or requirements for their proposed submachine guns to meet, the SEAL’s weapon of choice was the reliable and accurate 9mm m/45, Swedish K submachine gun. One of the Navy requirements for a submachine gun class weapon was the ability to drain water quickly from the receiver.

Problems with the military procurement of the Swedish submachine guns were eventually encountered due to Sweden’s long-standing position as a neutral country, along with their outspoken protest of U.S. involvement in the Vietnam War.

During the early spring of 1966, the U.S. Navy Department contacted Smith & Wesson representative Mr. George Ersham to inquire about the possibility of the U.S. company designing and manufacturing a weapon that would be similar in concept and operation to the Swedish K. By the fall of 1966, the Development Section of Smith & Wesson received an official written request from the Department of the Navy for the development of a new 9mm submachine gun. Corporation officials met with SEAL Team One at the Naval Amphibious Base Coronado, in San Diego, California, to discuss the project. During the meeting, Smith & Wesson officials were provided with a list of the characteristics desired in the proposed submachine gun. The rival Colt firearms company had the military market virtually sewn up at the time. Mr. Gunn recognized that a lucrative military order could help sustain his company’s future well into the 21st Century.

Mr. Dwayne Charron of the Research and Development Section of Smith & Wesson was chosen to head up the project. Mr. Charron was well qualified for the task, having a lot of experience with the development and design of many of the company’s firearms. The model designation assigned to the submachine gun project was the number 76. It was nothing other than a control number, having no other significance.

The X-Series Submachine Guns

Smith & Wesson routinely assigned a letter “X” prefix to experimental or preproduction projects. After a project had been developed and tested, blueprints were sent to the Engineering Department where final tolerances and dimensions were used to draw production blueprints. Firearms made from the prints were used to manufacture tool room models of the proposed gun. Those guns were designated with a letter “T” prefix for “Tool Room.” The letter “T” was occasionally used on a production weapon that had been modified.

The first experimental samples of the Model 76 were completed in the fall of 1966-1967 and were assigned serial numbers X-185 through X-219. The early X-185 gun lacked a buttstock and sights. On gun X-186, a folding stock and sights were added. Two X-prefixed guns, X-186 and X-219, were later modified for the caseless ammunition project. To make the weapon as light as possible, there was one prototype gun; X-188 was made with an aluminum alloy receiver. Later there was a request issued for nine additional aluminum receivers; these were serial numbered X-210 to X-218. Most of the receivers were not assembled into functioning weapons. Apparently, there were problems, and the aluminum receiver concept was abandoned.

By January 1967, a prototype weapon was completed and ready for extensive field-testing. At this point the magazine for the 76 project had not been developed, so modified Swedish K magazines were used. Due to cost considerations, it was decided not to key the barrel for consistent indexing with the receiver. This saved a few machining processes to the barrel and receiver. The weapon that was designed by the engineers at Smith & Wesson looked somewhat similar to the Swedish submachine gun it was to replace, but there were a number of differences. Primarily, the Smith & Wesson submachine gun was lighter in weight, more ergonomic, slightly smaller in size, handier, featured a more positive safety, and it was select-fire.

The T-Series Submachine Guns

During May 1967, the first 10 Tool Room submachine gun models had been assembled. They were assigned serial numbers T-1111 to T-1120. During testing, a few failure-to-feed stoppages occurred. The problem was traced to an oversized magazine housing and was easily solved by inserting a U-shaped piece of steel to align and secure the magazine.

The X and T models of the M76 were fabricated in a number of configurations for testing and evaluation purposes.

The production of the first test lot of 100 guns commenced on June 24, 1968. Each gun had a four-digit serial number with a “T” prefix. The “T” prefix indicated that the guns were completed in the Research and Development Department’s Tool Room and not regular production pieces. The serial numbers of the early pre-production models were marked on the left side of the magazine well. The “T” series models were often configured differently. Most of the T series guns lacked the barrel jacket as seen on production guns. The method of securing the barrel to the receiver was different on guns that lacked a barrel jacket. A barrel retaining catch was utilized, similar to that of the U.S. M3 submachine gun. The strut arms of the early stocks were straight while the later production models curved around the back of the receiver tube. The sides of the plastic grip were smooth. A total of 105 T prefix weapons were built by the Research and Development Department from November 1966 to April 1971. Most of the T-series weapons studied during the research for this article had a medium gray parkerized finish while most of the U-prefix production submachine guns were parkerized with a gray-green finish.

As the Tool Room models were refined, the factory began to fabricate fixtures and gages and provide drawings to outside vendors for components that were not made in-house.

After preliminary testing, a small lot of 100 Smith & Wesson T-series submachine guns were produced for further testing in-house and in the field. During the early months of 1968, the final design of the weapon began to materialize. After a few last-minute minor design changes were implemented, the weapon went into production as the Smith & Wesson Model No. 76–9mm Submachine Gun. In addition to the Navy contract, the Smith & Wesson Company had planned to offer its new American submachine gun to U.S. law enforcement agencies, for replacement of its aging Reising and Thompson weapons.

To facilitate manufacture of the M76 submachine gun, Smith & Wesson opened a completely new manufacturing facility called the Annex. Also, commonly known as Department 10, the 10,000-square-foot building was located on Stevens Street, in Springfield, Massachusetts. The new Smith & Wesson division began operations during 1968, specifically to manufacture the submachine gun. Department 10 had 20 employees in 1968 and was headed by foreman Lou Jarvis. While some parts were machined in the main plant, most of the welding and assembly was performed in the Annex building. Upon final assembly, the completed submachine guns were then transported back to the main plant for a final inspection before packaging and shipping.

The U-Series Production Model

The Model 76 submachine gun design was a basic, simple, but durable weapon primarily made from heavy sheet metal stampings. The receiver tube was produced from heavy 120-inch-thick seamless steel tubing. The inside of the thick receiver tube was broached (often-called “sand cuts”) to help prevent stoppages from sand or any foreign debris that may collect inside the receiver. The appendages: the sights, magazine housing and sling attachment points were heliarc-welded to the thick receiver tube.

The fixed sling loops were intended to employ the common U.S. issue M1 carbine sling. The ejector was also attached to the receiver tube by two vertical welds. The fixed magazine well was flared at the bottom for fumble-free insertion of a magazine. The trigger, trigger bar and sear were in a removable sheet metal housing that is located under the receiver tube. The trigger guard is also a simple steel stamping attached to the trigger housing by a single rivet. For use in Arctic climates, the trigger guard can be rotated out of position allowing the weapon to be operated with gloves or mittens. The Model 76 was following the concept of the World War II British Sten and U.S. M3 submachine guns: simple and cheap.

The 8-inch barrel can be easily removed for cleaning or replacement via a knurled barrel nut. A heavy, tubular shroud with 28 cooling ports was later introduced in order to protect the operator’s hands from an overheated barrel. The threaded barrel nut was incorporated as part of the shroud. The sights are calibrated for a 100-meter range and are nonadjustable. The Model 76 is capable of both semiautomatic and full-automatic fire, by means of an ambidextrous M16-style semiautomatic-automatic-safe selector lever.

The buttstock folds and locks to the left side of the receiver as to not interfere with the cocking handle if the weapon is fired with the stock folded. The Smith & Wesson 76 is finished in a military-style, medium gray-green phosphate; the M76 has an overall length of 20.25 inches with the stock in the folded position. With the stock extended the length is 30.38 inches. Loaded weight with a 36-round magazine is 8.67 pounds.

The first six production guns have unique serial numbers beginning with a letter “U” followed by six digits. These submachine guns were numbered U001001 through U001006. In June 1968, regular production began starting with serial number U101 until production ended with submachine gun serial U6100, built July 5, 1974.

The serial numbers of the production guns were marked on the right rear side of the receiver tube. There were a reported 6,000 production Model 76 weapons manufactured. A few minor variations appear in the production models. During 1969, the barrel jacket was changed from seamless tubing to a less expensive design made from a piece of flat sheet metal, which after cooling holes were punched into it, was rolled into a tube and welded along its seam. Another minor detail noted on some guns are two holes in the front of the magazine housing; the purpose of these holes is for a jig to hold the piece in place for a welding operation.

During July 1974, production of the Model 76 was terminated. The decision was made due to declining demand for pistol-caliber submachine guns, which were being replaced in law enforcement and military organizations by modern assault rifles.

The original retail cost of a Smith & Wesson Model 76 submachine gun in 1969 was $76.50. Today, all models of the Smith & Wesson M76 submachine guns are considered Curio & Relic firearms by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives.

The United States Navy purchased a number of the Model 76 submachine guns and classified them: Navy Mark 24 Mod 0, NSN 1005-01-013-6050. Each of the weapons was issued with four magazines. The SEALs also requested that Smith & Wesson design a suppressor (silencer) for “their” Model 76s, to reduce the weapon’s report and muzzle flash. Smith & Wesson’s Dwayne Charron designed the Smith & Wesson M76 suppressor as a complete unit that would easily replace the weapon’s standard barrel.

The barrel inside of the Smith & Wesson suppressor has a series of ports to reduce the velocity of standard 9mm ammunition to subsonic levels and to eliminate the sound generated when the bullet exceeds the speed of sound after leaving the barrel. Mr. Charron received patent number 3,713,362 on June 30, 1973, for his suppressor design. Production of the suppressors built by Smith & Wesson was limited to a few units.