HONEYWELL MULTIPLE GRENADE LAUNCHER Mk18 Mod 0 (HMGL) 40mm HONEYWELL MULTIPLE GRENADE LAUNCHER Mk18 Mod 0 (HMGL) 40mm Manufactured by Honeywell Corporation, Hopkins, Minnesota - This weapon is a manually operated (hand cranked) belt fed, rapid-fire 40mm grenade launcher designed to provide coverages of targets with high explosive fragmenting grenades. It will fire at variable rates up to 250 rounds per minute at ranges from approximately 328 yards to 2,200 yards. The rotary spilt breech, utilized in this weapon, allows straight through feeding of ammunition and eliminates the need for a reciprocating bolt, extraction of ammunition from a belt, extraction from a chamber and ejection for the weapon. The ammunition is belted in a fabric (fiberglass tape) at the correct intervals, the empty cartridge remain in the belt as they are fired. The firing rate may be continuously varied from 1 to 250 rounds per minute in a hand crank operation, governed only by the operator. If higher firing rates were desired, this could be achieved by motorizing the drive mechanism. Effective range of 3937 yards. Maximum range of 4,593 yards. Weight of weapon is 19 lbs, and can be lightened by the use of castings with ribs and bosses rather than wrought machined parts. Notes: "This weapon, MK 18 Mod 0, represents the introduction in 1962 of a new concept n weaponry, that of a rapid fire grenade launcher. It is the first step past the single-shot M79 grenade launcher. The 40mm Mk18 utilizes a spilt breech concept which has been previously used but has some original characteristics based on the introduction of a mechanism to allow the top rotor to move vertically and synchronizes the bottom rotor. Between 1965 and 1968, approximately 1200 of the Mk18 Mod 0, 40mm Multiple Grenade Launchers were produced by the Honeywell Corporation and Aeronautical Products Division, Hopkins, Minnesota. The first patent application was filed by Honeywell in 1964, however, the initial development work commenced in late 1962. The concept was originally proposed during a study on the behavior of fuzes for the M79 grenade launcher ammunition. Honeywell had anticipated the need for a simple, inexpensive and extremely mobile rapid fire weapon that could provide a team of two men with an effective capability for delivering large quantities of explosive grenades within a limited range primarily for suppressive and defensive fire purposes. The development of the 40mm cartridge grenade with its two stage propelling system (essentially an impulse system) made such a weapon possible. The high-low pressure propelling system utilized in the 40mm cartridges permits the use of a spilt breech mechanism which allows the weapon to be extremely light and simple....Test Result - From results of the evaluation it was concluded that the prototype 40mm Mk18 Mod 0 grenade launcher as received from Honeywell Inc. will fire 5000 rounds without wearout failures. However, during the evaluation, the performance of the gun, especially during the first 3000 rounds was unsatisfactory because of the high stoppage rate due to faulty ammunition belting, inadequate firing pin protrusion, and the rough cycling action of the weapon at the higher rates of fire. It was also recommended that the firing mechanism be modified to prevent inadvertent firing of the round during movement of the firing pin from the safe to fire position. While this concept was soon declared obsolete due to the introduction of the much needed automatic 40mm grenade launcher system, Honeywell's contribution to the state of the art work was outstanding." - George M. Chinn "HONEYWELL GUN FOR VIETNAM PATROL BOATS by Charles D. LaFond. Minneapolis - Hand-cranked Multiple Grenade (40-mm) Launchers will see operational use aboard the Navy's new PBR river patrol boats in Vietnam. More than 500 of the new weapons have been ordered by the Navy from Honeywell, Inc, which developed the weapon in 1963, under contracts of more than $750,000. Designed for use on a low tripod, the small lightweight weapon is capable of firing up to 375 meters at a rate of over 250 rounds a minute. For its Navy role, the gun is expected to be mounted atop a 50-caliber machine gun on the stern of each PBR. Over 100 of the new craft have been procured to protect South Vietnamese river traffic and to reduce the Viet Cong water operations. Since the patrol craft were previously armed with only three small machine guns and a few single-shot, hand-held, M-79 grenade launchers, the rapid-fire launcher is expected to increase their combat effectiveness significantly, particularly against obscured shore targets and snipers. Developed over three years ago by Honeywell's Ordnance Div., the launchers were extensively tested by the Naval Ordnance Laboratory - White Oak in Silver Spring, Mad., and at the Naval Weapons Laboratory, Dahlgren, Va. Under the first Navy contract, awarded in March, 1966, Honeywell delivered 201 weapons; another 330 will be supplied by May under a second Navy contract let last October. First units were delivered to Vietnam last month. Although some of the weapons may have seen use, report on their effectiveness in action are not yet available. The Army purchased 20 of the new weapons last July for evaluation and is currently testing them at Aberdeen Proving Ground, Md. Simple, effective - Working on their own time, two Honeywell engineers built the first operating weapon in 1963, and then demonstrated its effectiveness and utter simplicity to Honeywell officials. The firm was convinced and a development effort was funded, leading to the current program. The result of their project is a 26-lb. weapon standing 1 ft. high and measuring about 2 ft. in overall length. It employs a spilt breech to accept 40-mm (low velocity) grenades fed straight through on a belt. Spent shells remain in the Mylar-reinforced Dacron belt. In operation, the hand crank is rotated to feed the belted rounds into the breech and to 'cock' and release a spring-loaded firing pin. Two rounds are fired during each full crank revolution; thus, loading occurs at 3 and 9 'o'clock,' firing at 6 and 12. A three position know is located at the rear of the gun for 'Fire,' 'Safe,' and 'Load' control. For the Navy, a 48-round ammo box weighing 35 lbs. is used. A 19-lb., 24-round box also is available for use in the field. Belts are hand-loaded and may be reused up to 4 or 5 times, Honeywell disclosed. Improvements seen - It is probable, said one Honeywell official, that a family of launchers will evolve in time. For example, engineers here are considering addition of an electric drive for fully automatic fire. Also, developers are presently studing means for modifying and beefing up the weapon so that it may be used for both the low- and high-velocity (1,500 meter) range) 40-mm shells. (The latter type are currently fired from the M-75 automatic gun using a metal-link belt.) Technology Week, February 6, 1967. References: Chinn, George M. THE MACHINE GUN. Vol. V. Edwards Brothers Publishing Co. Ann Arbor, Mi. 1987. Photos and information from: Pierangelo Tendas & Roger Desbois

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