No tools are needed to set the fuze, and the setting can be changed several times without damaging the fuze. When a large number of cartridges are needed for a mission, they may be removed from the containers and prepared. d. The gunner recovers the baseplate to the area designated by the squad leader. The squad leader indicates the direction of fire when mounting. The cannon assembly consists of the barrel that is sealed at the lower end with a removable breech plug, which houses a removable firing pin (Figure 4-3). If the mortar section is to operate quickly and effectively in accomplishing its mission, mortar squad members must be proficient in individually assigned duties. It has four function settings: PRX (proximity) causes the cartridge to explode between 3 and 13 feet above the ground; NSB (near-surface burst) causes the cartridge to explode up to 3 feet above the ground; IM (impact) causes the cartridge to explode on contact; and DLY (delay) incorporates a 0.05-second delay in the fuze train before exploding the cartridge. Target terrain, such as ice and dry sand, gives lowest burst heights, whereas water and wet ground give highest burst heights. If the round fires, the mortar is re-laid on the aiming point and firing is continued. There is a selector on the lower shaft for non-delay or delay impact action. This may cause the firing pin to ignite the charges if the cartridge is dropped on the fin end (. The RSTA squadron only receives the 120mm mounted mortar, there is no augmentation dismounted maneuvers. .50: AP, M2 AND CARTRIDGE, CAL. The gunner unlocks the barrel clamp and rotates the barrel, unlocking the breech plug from the rotating socket of the baseplate. It is fitted with a safety wire and pin that are removed immediately before firing. This cartridge is ballistically matched to the M374A2, M374A1, and M375 HE cartridges, and weighs about 9.12 pounds. Section I. The muzzle end has a short tapered lead-in which acts as a . Correct way to open an ammunition box. High explosive is used for both fragmentation and blast effect against personnel and light-skinned vehicles. Designed by Thingsym. He must ensure that the ball-shaped end of the locking rod is secured in its recess by the locking latch. d. The gunner removes the sight from its case, mounts it on the mortar, and sets a deflection of 3200 mils and an elevation of 1100 mils. It has a time setting of up to 25 seconds. It was even a tool used by airborne units, and was dropped in parachute bundles during Operations Neptune, Market Garden, and Varsity. a. 81mm 120mm 60mm . Each round is stenciled with the ammunition lot number, type of round, type of filler, and caliber. If it gets wet or dirty, it must be wiped off at once. See Chapter 3, paragraph 3-14 for a detailed discussion of malfunctions. Before the mortar is mounted, the squad must perform premount checks. He stands to the rear of the baseplate and supports the barrel until the bipod is fitted. (6) The primer cartridge is checked for damage or dampness. The section leader, acting as FDC, has one deflection instead of two or more. c. The assistant gunner stands to the right of the mortar, facing the barrel and ready to load. High angles of approach (near vertical) give the lowest burst heights. The cartridge can be fitted with the M524-series, M526-series, M567, or M532 fuzes. Propelling charges are covered or protected from dampness or heat. With standard mortar, the maximum effective range is close to 4,000 metres; with a long-range system, this increases to nearly 4,500 metres. c. Authorized Cartridges. The assistant gunner checks the bipod and ensures that--. Features: The M252 81mm Medium Extended Range Mortar is a crew-served, medium weight mortar which is highly accurate and provides for a greater range (4,500 meters to 5,650 meters) and lethality than the previous 81mm mortar. Home; Swifty. The mortar should be within two turns of center of traverse when the task is compete. MFCS Dismounted. Despite its weight though, the 81mm mortar was an important part of the Table of Organization and Equipment of U.S. Army and U.S. Marine Corps maneuver battalions throughout World War II. c. After the gunner has announced, "Up," the squad leader should check the mortar to determine if the exercise was performed correctly. Light tree foliage and light vegetation affect the height of burst only slightly, but dense tree foliage and dense vegetation increase the height of burst. This round may be stored in a horizontal position. (8) To help minimize the occurrence of short rounds and or duds, unpackaged ammunition that has been dropped should not be fired. A spring-loaded locating catch is behind the elevating gear housing, which locates the plain leg in its supporting position for level ground. Any target that requires that elevation, or a lower one, cannot be engaged from that position. The cartridges are painted olive drab with yellow markings. (4) The bipod locking latch is locked, securing the barrel clamps. M120/M121 120 mm Mortar. a. If, upon removal of the safety wire, a buzzing sound in the fuze is heard, the round should not be used. He levels all bubbles. (4) The leg-locking handwheel is hand tight. Cartridges assembled with the M532 fuze must be fired above charge 0. REFER DEFLECTION TWO EIGHT SEVEN FIVE (2875), REALIGN AIMING POSTS. Examples are: The mortar is within two turns of center of traverse. When firing under the control of an FDC, he reports to the FDC that mask clearance cannot be obtained at a certain elevation. Complete cartridges are always handled with care. The equipment is placed out the same as for the gunner's examination (Chapter 9). The squad leader picks up the sight case and the two aiming posts, and moves to the exact position where the mortar is to be mounted. b. The M374 cartridge is fitted with the M90 propelling charge. Referring and realigning aiming posts ensure that all mortars are set on the same data. c. The assistant gunner disengages the barrel clamps and moves the bipod from the immediate area of the mortar position. The 0-second boss is wider and differs in shape from the other body bosses; the safe setting position is indicated by the letter "S" on the fuze body. The gunner levels the elevation bubble by turning the elevation micrometer knob and reading the setting on the elevation scale and elevation micrometer--this setting is the minimum mask clearance. The fuze should already be fitted to the cartridge. These cartridges are used first in subsequent firing so that once-opened stocks can be kept to a minimum. The second ammunition bearer retrieves the aiming posts. He may assist the gunner in shifting the mortar when the gunner is making large deflection changes. The M252 medium mortar offers a compromise between the light and heavy mortars. The lower clamp is shaped and bored on each side to house the buffer cylinders. The components of the mortar consist of a cannon, mount, and baseplate. Ammunition is typed according to use (Table 4-2). VERY NICE condition! If the situation allows for a longer waiting period, the dud can be considered safe for handling after 40 hours. c. The M374A3 HE cartridge is constructed from pearlitic malleable cast iron and contains about 2.10 pounds of composition B explosive. (1) The barrel is clean and free from grease and oil both inside and out. (1) Marking on container. Tabulated data. Red phosphorus cartridges (M252 only) are stored the same as HE cartridges. The mortar is mounted and the sight is installed. [1] [2] Many countries use or used an 81 mm mortar in their armed forces. This may preclude moving the bipod. A locked padlock The round has a burst height of 600 meters and provides illumination for about 60 seconds for an area of about 1,200 meters. Other armies count on 81mm mortar families. The powder increments, mainly, should not be exposed to direct sunlight. The 0-second boss is wider and differs in shape from the other body bosses; the safe setting position is indicated by the letter "S" on the fuze body. The settings are obtained from the range tables and are applied using a wrench (number 9239539) or a 1 3/4-turn open-end wrench. Washington DC 20310-0107, ADRP - Army Doctrine References Publications, ATTP - Army Tactics, Techniques, and Procedures, FY Publication Status Report (CAC required for access), Publishing Resources (CAC required for access), PC/PCO/FMO/EPCO Directory (CAC required for access), usarmy.pentagon.hqda-apd.mbx.customer-service@army.mil, GUN, MACHINE, CAL. While the assistant gunner supports the barrel, the gunner slackens the leg-locking handwheel, releases the locating catch, and positions the plain leg. Proximity fuzes withstand normal handling without danger of detonation or damage when in their original packing containers or when assembled to projectiles in their packing containers. OPERATOR`S MANUAL FOR MORTAR, 81-MM, M252 (NSN 1015-01-164-6651) (EIC 4SK){TM . c. Mechanical Time. The floating firing pin located within the primer has approximately 1/16 of an inch to move around. The assistant gunner attempts to maintain the traversing mechanism on a horizontal plane. Ammunition is made and packed to withstand all conditions ordinarily encountered in the field. b. Mount The M1 was a derivative of the French mle 27/31 system (itself an improved form of the Stokes Trench Mortar of World War 1 fame) and slightly altered to suit American needs. 4-12. a. Long Range PGK. If the round does not fire, the gunner tests the barrel for heat. The gunner checks the baseplate and ensures that--. The cartridge weighs about 9.12 pounds. He lays for deflection, taking the proper sight picture. MC Medical Guide; Client-side mods; TFAR 1.x for players; The types of fuzes described in this paragraph are point detonating, proximity, mechanical time, multioption, and dummy. M3A1 Baseplate Trenches are dug to prevent water from flowing under the pile. The sight is laid on two aiming posts (placed out 50 and 100 meters from the mortar) on a referred deflection of 2800 mils and an elevation of 1100 mils. a. Point-Detonating. c. The first ammunition bearer checks the barrel and ensures that--. 4-11. Short cartridges can be expected when firing below charge 4. d. Climatic Effects. 1:4 For the 81MM Mortar System: X NSN (LIN): 1015-01-441-3113 : STAFF SECTION, CLEANING, ARTILLERY 1:4: Maximum Range (meters): 7,240 (with standard fuze) . Cartridges assembled with the M524 (A1, A2, A3, or A4) fuze are for use by the U.S. Marine Corps and U.S. Navy only. Official websites use .mil The first ammunition bearer holds the barrel until the assistant gunner has removed the mount. The M889 HE cartridge (M252 onlyXUS Marine Corps) is of the same construction as the M821 cartridge in every detail except the fuze, which is the M935. Share sensitive information only on official, secure websites. The first ammunition bearer shakes the barrel to dislodge any remnants from the last round fired, and he lowers the barrel into the rotating socket of the baseplate. The term "indirect fire" means firing at an enemy without having a. c. The first ammunition bearer ensures that each cartridge is clean, the safety pin is present, and the ignition cartridge is in good condition. f. The open end of the socket must continue to point in the direction of fire. The safety/packing clip should be removed when the cartridge is unpacked. The baseplate (Figure 4-5) is of one-piece construction, and supports and aligns the mortar for firing. 9301 Chapek Road., Bldg.1458 This round must be stored in a vertical position. They use the M5 propelling charge that consists of eight cloth bags attached to the tail unit. He indicates the initial direction of fire by pointing in that direction and commands ACTION. The fuzes may be used for day or night operations. All mortar cartridges are painted to prevent rust and to identify their type. h. Where the ground is uneven and there is no level surface for the bipod, the gunner can adjust the plain leg. (b) In selecting the exact mortar position, the leader looks quickly for mask clearance and overhead interference. Additionally, they carry the 81mm M252 mortar that can only be used in a dismounted capacity. The fuze contains a delayed arming feature that ensures the fuze remains unarmed and detonator safe for a minimum of 1.25 seconds of flight. The M252 is highly accurate up to ranges of 4500m to 5700m depending on the The enemy will use them. The Mark 4 and 5 barrels were introduced during World War 2 and have a much increased range. If it is necessary to leave the ammunition uncovered, it should be raised on dunnage at least 6 inches above the ground. The M375 cartridge uses the M90 propelling charge while the M375A2 and M375A1 cartridges use the M90A1 propelling charge. (a) Since the mortar is normally mounted in defilade, there could be a mask such as a hill, tree, building, or rise in the ground. 0.30, BROWNING, M1917A1; GUN, MACHINE: CAL. The BAD is removed only by qualified maintenance personnel. The fuze setter, M25, sets M84-series time fuzes. All rounds are colored according to their type. More uniform firing is obtained if ammunition is kept at the same temperature. The mortar squad consists of five men (Figure 4-1). To set for delay, the selector slot should be rotated clockwise until it is aligned with the "D" mark on the ogive. Increments removed from cartridges before firing should be placed in a metal or wooden container located outside the firing vehicle/position at least 25 meters away. M224A1 60 MM LWCMS Mortar The 60mm mortar, M224A1 Lightweight Company Mortar System (LWCMS), is a smoothbore, muzzle loaded, high angle of fire weapon. Table 4-1. The barrel clamps are then closed. The gunner can depress the barrel, if necessary, to provide easier access to the firing pin. This section contains information on how to prepare the 81-mm mortar, M252, for firing, how to conduct safety checks, and, if a misfire should occur during firing, what actions the crew applies to remove the cartridge from the barrel. Finally, the assistant gunner loosens the leg-locking handwheel, presses the spring-loaded locating catch, and raises the plain leg behind the buffer cylinders until it touches the traversing handwheel. The following safety checks must be enforced before firing the mortar. Proximity-fuzed short cartridges, which are duds, contain a complete explosive train and impact element. The M375A3 cartridge is ballistically similar to the M374A3 (HE) cartridge. Fuzes are not disassembled. The terms cannon and barrel are used interchangeably in this chapter. After the mortar is mounted, the gunner makes a thorough check. The propelling charge is contained in four horseshoe-shaped, felt-fiber containers or nine wax-tested, cotton cloth, bag increments. Figure 4-7. Then he relocks the barrel clamp. News. A safety latch located at the side of the recess is used to secure the ball. The 81-mm mortar, M252, is a smooth-bore, muzzle-loaded, high-angle-of-fire weapon. 81-mm MORTAR, M252 The 81-mm mortar, M252, delivers timely, accurate fires to meet the . Types of rounds, classification, and characteristics for the 81-mm mortar, M252. b. (7) When opening an ammunition box, the ammunition bearer ensures the box is horizontal to the ground, not nose- or fin-end up. d. The first ammunition bearer stands to the right rear of the mortar. They are fuzed with the M524-series, M256-series, or M532. An internal clock mechanism provides nine seconds of safe air travel (610 to 2,340 meters along trajectory for charge 0 through 9, respectively). e. The gunner centers the elevation bubble. At the muzzle end is a cone-shaped blast attenuator device (BAD) that is fitted to reduce noise. The standard infantry support weapon is the M-252 81mm mortar, which lobs a 10 lb. The barrel clamp, which consists of an upper and lower clamp, is situated at the top. 107 Army Pentagon It uses the M219 propelling charge and weighs about 9.1 pounds. e. The second ammunition bearer stands to the right rear of the mortar behind the ammunition bearer. General Dynamics Ordnance and Tactical Systems is the leading manufacturer of propellants for 60mm, 81mm and 120mm Mortar Systems. .50 MACHINE GUN, M55 AND MACHINE GUN, CAL. These are NDI items . b. He exposes 1 inch (25 millimeters) of cross-level shaft and folds the handle. The fuze is not intended to function at charge 0. high-explosive bomb at a range of about three miles. This section discusses the. When set at delay, the fuze train causes a 0.05-second delay before functioning. The gunner moves the mortar as the assistant gunner steadies it. The vertical cross line of the sight is on the left edge of the aiming point. The aluminum tail assembly has six integral fins equally spaced around the rear, which stabilize the round in flight. In the U.S. Army and U.S. Marine Corps, it is normally deployed in the mortar platoon of an infantry battalion. The obturating ring ensures equal muzzle velocities in hot or cold barrels by keeping all the gases in the barrel until the cartridge has fired. Prev - Mk6 Mortar range table for charge 0 Next - Mk6 Mortar range table for charge 2 . Both the 60mm and 120mm mortar rounds use White Phosphorus. End this starting train with not less than 1 meter of inert material (dry grass, leaves, or newspapers). The safety wire must be removed before firing. The cannon has a crew-removable breech plug and firing pin. They contain about 2.10 pounds of composition B explosive. SMALL DEFLECTION AND ELEVATION CHANGES. If you look at the table above, you'll see that at 1.5km range, 120mm mortars have nearly 33% more dispersion than 80mm mortars.Try testing 80mm mortars and 120mm mortars at 1.5km against . Both the M90 and M90A1 propellants are in nine wax-tested, cotton cloth, bag increments assembled to the tail unit. With the mortar mounted and the sight installed, the gunner lays the sight on the two aiming posts (placed out 50 and 100 meters from the mortar) on a referred deflection of 2800 mils and an elevation of 1100 mils. The first table is a chart that shows range and elevation for firing particular mortar shells. The gunner removes the sight and places it in the case with 3200 deflection and 0800 elevation indexed. (5) Do not leave unused increments unburned in combat operational areas.