The adjustment ring has six raised ribs for use in conjunction with fuze setter, M25, and a setting indicator rib (marked SET) about half the height and width of the other six ribs. It is light enough to be portable when broken down into. The 81-mm mortar, M252, is a smooth-bore, muzzle-loaded, high-angle-of-fire weapon. Safety before firing is provided by a safety wire, which must be removed just before firing. Joint Tables of Allowance; PB - Professional Bulletins; STP - Soldier Training Publications; TC - Training Circulars; . He must not stand directly behind the mortar. A locked padlock The M252 81 mm medium weight mortar is a British designed smooth bore, muzzle-loading, high-angle-of-fire weapon used for long-range indirect fire support to light infantry, air assault, and airborne units across the entire front of a battalion zone of influence. When set at SQ, the fuze functions on point impact or graze contact. The fuze is not intended to function at charge 0. After the bands are broken and the box opened, the rounds should be removed by allowing them to roll out along the lid of the box (Figure 4-8). Proximity (VT). It has no safety pins or wires to reduce preparation time. The company level vehicles also carry a vehicle-mounted 120mm mortar, which is augmented by the 60mm M224 mortar for dismounted use. An internal clock mechanism provides nine seconds of safe air travel (610 to 2,340 meters along trajectory for charge 0 through 9, respectively). High explosive is used for both fragmentation and blast effect against personnel and light-skinned vehicles. The contents of ammunition containers are shown by markings. The firing pin must be replaced and the bore swabbed. Those cartridges assembled with the M524 (A1, A2, A3, or A4) fuze are for use by the US Marine Corps and US Navy only. Cartridges assembled with the M532 fuze must be fired above charge 0. c. Authorized Cartridges. The mortar squad consists of five men (Figure 4-1). It is set using the bladed end of the M18 fuze wrench. The gunner stands to the left side of the mortar where he can manipulate the sight, elevating handwheel, and traversing handwheel. The safety wire must be removed before firing. HE ammunition is used against personnel and materiel. c. The gunner grasps both ends of the traverse screw assembly and supports the mortar during the subsequent drill. Additional information is included on an ammunition data card inside each container. The 81mm mortar is a portable, mobile, medium mortar at the infantry's disposal. Its range and explosive power is greater than the M224, yet it is still light enough to be man . The propellant increments are ignited, which produce rapidly expanding gases that force the cartridge from the barrel. The ignition cartridge strikes the firing pin and detonates, which causes a flash that passes through the radial holes in the shaft. An M18 fuze wrench is used to change settings. Upon completion of any bipod movement on the barrel, the gunner ensures that the firing pin recess is facing upward. Army Publishing Directorate The first table is a chart that shows range and elevation for firing particular mortar shells. All elements given in the fire command are repeated by the squad. The barrel is then rotated a quarter turn to unlock it from the socket, and it is placed in an area designated by the squad leader. It arms within a maximum of 2.50 seconds. He may assist the gunner in shifting the mortar when the gunner is making large deflection changes. If the situation allows for a longer waiting period, the dud can be considered safe for handling after 40 hours. It is designed to be fired in the indirect fire mode, cannot be fired handheld, and normally utilizes a FDC. on Amazon.com. Propelling charges are covered or protected from dampness or heat. d. When the barrel reaches the horizontal position, and not before, the assistant gunner moves the thumb of each hand over the muzzle. 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. The cartridge is painted olive drab with yellow markings. Cartridges assembled with the M532 fuze must be fired above charge 0. d. Climatic Effects. M3A1 Baseplate c. The M375A2, M375A1, and M375 cartridges may also be used. An air cavity can form on one side of a cartridge to unbalance it, causing instability in flight. This cartridge is ballistically matched to the M374A2, M374A1, and M375 HE cartridges, and weighs about 9.12 pounds. He performs other duties as the squad leader directs. b. As soon as the sight data are announced, the gunner places it on the sight. An 81 mm mortar is a medium-weight mortar. 81mm 120mm 60mm . (703) 614-3727, Office of the Chief Information Officer (b) In selecting the exact mortar position, the leader looks quickly for mask clearance and overhead interference. A .mil website belongs to an official government organization in the United States. Do not burn increments in piles but spread them in a train 1 to 2 inches deep, 4 to 6 inches wide, and as long as necessary. 60MM M224A1. How the RCGM works: Target coordinates are programed into the RCGM using a portable GPS setter. (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. With the clamps facing away from him, the assistant gunner traverses the buffer carrier to the traversing handwheel and folds the handle. SMALL DEFLECTION AND ELEVATION CHANGES. The BAD is removed only by qualified maintenance personnel. FT 81-AI-3 Firing Tables Mortar, 81mm: M28A1 and M29 Mortar 81mm Self propelled M125A1 and M125 Carrier, 81mm Mortar Tracked XM755 [US Army.] REFERRING OF THE SIGHT AND REALIGNMENT OF AIMING POSTS USING M64 SIGHT. A securing strap is attached to the plain leg for securing the bipod in the folded position. Theme by TechDoc. The tabulated data of the 81-mm mortar, M252, are shown in Table 4-1. The traversing screw assembly is fitted to the clamp assembly, which is pivoted in the center on an arm attached to the elevating leg. Each squad member should be able to perform all the following premount checks: a. It has a time setting of up to 50 seconds. a. Cartridges are shipped with a complete propelling charge, an ignition cartridge, and primer. The M252 medium mortar offers a compromise between the light and heavy mortars. 4-4. Figure 4-7. When cartridges have been prepared for firing, but are not used, all powder increments and safety wires are replaced. Home; Swifty. The American M1 81mm Mortar, like the upcoming M2 60mm Mortar, was based on a French design by Edgar William Brandt (1880-1960). They are assembled with either an M524-series, M526-series, or M567 fuze. He knocks down the near aiming post and proceeds to the far aiming post. 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. Several types of HE ammunition are used in the 81-mm mortar, M252. The M301A3 cartridge has a cylindrical body that contains an illuminating candle and parachute assembly. The gunner checks the baseplate and ensures that--. If the fuze does not function as set, it automatically functions at the next lower setting. It is painted white with black markings. However, since explosives are affected by moisture and high temperature, they must be protected. It engages the 1 3/4-inch flats on the setting ring or the fuze head. The gunner is given an administrative command to lay the mortar on a deflection of 2860 or 2740 mils. 4-10. b. 81-mm MORTAR, M252 The 81-mm mortar, M252, delivers timely, accurate fires to meet the . . *FREE* shipping on qualifying offers. The mortar is mounted and the sight is installed. (2) The barrel is locked to the baseplate, and the open end of the socket points in the direction of fire. When a large number of cartridges are needed for a mission, they may be removed from the containers and prepared. 1:4 For the 81MM Mortar System: X NSN (LIN): 1015-01-441-3113 : STAFF SECTION, CLEANING, ARTILLERY 1:4: The cartridge weighs about 9.4 pounds. The squad leader points to the exact spot where the mortar is to be mounted. Red phosphorus cartridges (M252 only) are stored the same as HE cartridges. c. Upon receiving the command REFER, REALIGN AIMING POST, two actions take place at the same time in the mortar squad. e. The squad leader picks up the aiming posts and sight. Standard A ammunition for the M29A1 mortar is Standard B for the M252 mortar (, Light green Yellow band with red markings. Each cartridge weighs about 10 pounds and is provided with the M223 propelling charge, consisting of four horseshoe-shaped increments fitted around the tail. (1) The barrel is clean and free from grease and oil both inside and out. No tools are needed to set the fuze, and the setting can be changed several times without damaging the fuze. c. The first ammunition bearer ensures that each cartridge is clean, the safety pin is present, and the ignition cartridge is in good condition. 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. The following are authorized (Standard B) cartridges for the 81-mm mortar, M252: Each cartridge has fins around the tail to stabilize it in flight and to cause it to strike fuze-end first. 81 mm HE mortar projectiles generally contain anywhere between 400 g and 680 g of HE and have a maximum range of approximately 6,500 m. 82 mm HE mortar projectiles generally contain anywhere between 392 g and 680 g of HE and have maximum ranges of between 3,000 - 5,500 m. 9301 Chapek Road., Bldg.1458 The M751 is fitted with a smoke charge that operates on impact. It comes preset to function on SQ/IMP, and the selector slot should align with the SQ mark on the ogive. At the command, MARCH ORDER, the squad places the mortar, equipment, and ammunition in the squad vehicle and trailer. a. To prepare for firing, the slot is aligned in the striker with SQ or delay using the M18 fuze wrench. I say 120s are bad because they suffer from terrible dispersion even when not shooting at 6km. It uses the M772 mechanical time fuze and weighs about 10.6 pounds. When the baseplate is in position, the first ammunition bearer lowers the breech plug into the rotating socket and rotates the barrel a quarter of a turn to lock it. d. The gunner rough levels the cross-level bubble by making the bubble bounce from one side to the other. g. The barrel clamps can be moved along the barrel to counter large changes in elevation. It can be set from 3 to 55 seconds at half-second intervals. The following safety checks must be enforced before firing the mortar. XM1210. General Dynamics Ordnance and Tactical Systems is the leading manufacturer of propellants for 60mm, 81mm and 120mm Mortar Systems. b. Attached to the right of the screw is the traversing handwheel. c. The assistant gunner moves into position to the front of the bipod on his right knee and grasps the bipod legs (palms up), lifting until they clear the ground enough to permit lateral movement. He places his thumbs alongside the forefingers, being careful to keep both hands away from the muzzle. At extreme temperatures (below -40 degrees Fahrenheit and above 125 degrees Fahrenheit), it is not unusual to experience an increase in malfunctions proportionate to the severity of conditions. b. The mortar is within two turns of center of traverse. Maximum Range (meters): 7,240 (with standard fuze) . M252A1 81mm Mortar: Maximum Range (meters): 5,935; Ammunition: War reserve HE (M821A3), red phosphorus smoke (M819), visible light illumination (M853A1), infrared illumination (M816), war reserve and training HE (M889A4), and FRP . Since phosphorus liquefies at about 100 degrees Fahrenheit, the ammunition is protected against an uneven rehardening of the filler. There is a selector on the lower shaft for non-delay or delay impact action. During firing, the breech plug on the barrel is sealed and locked to the rotatable socket in the baseplate. Types of rounds, classification, and characteristics for the 81-mm mortar, M29A1 (Standard B for the 81-mm mortar, M252). The propelling charges are assembled around the fin assembly shaft. They use the M5 propelling charge that consists of eight cloth bags attached to the tail unit. Mount, M177, in folded position. If the mortar section is to operate quickly and effectively in accomplishing its mission, mortar squad members must be proficient in individually assigned duties. d. The gunner recovers the baseplate to the area designated by the squad leader. Fort Belvoir, VA 22060 f. The open end of the socket must continue to point in the direction of fire. TM - Technical Manuals (Range 9) TM - Technical Manuals (Range 10) TM - Technical Manuals (Range 11-4) TM - Technical Manuals (Range 11-5) . b. c. The assistant gunner lifts the bipod and stands it on its elevating leg so that the elevating handwheel is to the rear and the plain leg is to the front. It uses the M185 propelling charge that consists of eight increments fitted into the spaces between the fins and held by a propellant holder. The air burst over average types of soil ranges from 1 to 6 meters, depending on the angle of approach. (2) Color code. ), FIRING TABLES FOR CANNON, 155MM HOWITZER, M185 ON HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A1 HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A1B HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A2 HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A3 HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A3B AND HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A4 AND CANNON, 155MM HOWITZER, M284 ON HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A5 AND HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A6 AND CANNON, 155MM HOWITZER, M199 ON HOWITZER, MEDIUM, TOWED, 155MM, M198 AND CANNON, 155MM HOWITZER, M776 ON HOWITZER, MEDIUM, TOWED, 155MM, M777A1 FIRING PROJECTILE, HE, M483A1 (S&I BY PROP SEE DETAILS, FOOTNOTES), FIRING TABLES FOR, CANNON, 155MM, HOWITZER, M185 ON HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, 109A1 HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, 109A1B HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A2 HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A3 HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A3B AND HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, 109A4 AND CANNON, 155MM, HOWITZER, M284 ON HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, 109A5 AND HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, 109A6 AND CANNON, 155MM, HOWITZER, M199 ON HOWITZER, MEDIUM, TOWED, 155MM, M198 AND CANNON, 155MM HOWITZER, M776 ON HOWITZER, MEDIUM, TOWED, 155MM, M777A1 FIRING PROJECTILE, HERA, M549 PROJECTILE, HERA, M549A1 (S&I BY PROP SEE DETAILS, FOOTNOTES), FIRING TABLES FOR CANNON, 155MM HOWITZER, M185 ON HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A1; HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A1B; HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A2; HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A3; HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A3B; HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A4 AND CANNON, 155MM HOWITZER, M284 ON HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A5, M109A6 AND M109A7 AND CANNON, 155MM HOWITZER, M284A2 CHROME ON HOWITZER, MEDIUM, SELF-PROPELLED, 155MM, M109A6 AND M109A7 AND CANNON, 155MM HOWITZER, M199 ON HOWITZER, MEDIUM, TOWED, 155MM, M198 AND CANNON, 155MM HOWITZER, M776 ON HOWITZER, MEDIUM, TOWED, 155MM, M777, M777A1 AND M777A2 AND CANNON, 155MM HOWITZER, M776 CHROME ON HOWITZER, MEDIUM, TOWED, 155MM, M777A2 FIRING PROJECTILE, HERA, M549 AND PROJECTILE, HERA, M549A1 (S&I BY PROPONENT, SEE DEAILS, FOOTNOTES. The elevation change announced must be less than 90 mils and more than 35 mils. After the barrel cools, the gunner removes the sight and firing pin. The components of the mortar consist of a cannon, mount, and baseplate. Ammunition is typed according to use (Table 4-2). If the barrel is cool enough to handle, the crew removes the round as described below. To make the shift, the gunner places the fingers of his right hand in the muzzle and his left hand on the left leg. It can be fitted with either the M567, M524, or M532-series fuzes. An ammunition lot number is assigned to each ammunition lot, which is marked on each cartridge and packing container. News. Examples are: Powered by Hugo. (2) The fin and fuze assembly must be checked for tightness and damage. A spring-loaded locating catch is behind the elevating gear housing, which locates the plain leg in its supporting position for level ground. 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. If the round does not fire, the gunner tests the barrel for heat. The M252 is highly accurate up to ranges of 4500m to 5700m depending on the The platoon leader commands the platoon and supervises the training of the elements. 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. The M375 cartridge uses the M90 propelling charge while the M375A2 and M375A1 cartridges use the M90A1 propelling charge. The gunner then kicks the barrel several times with his heel in an attempt to dislodge the round. The M853 cartridge (M252 only) has a cylindrical body that contains an illuminating candle and parachute assembly. The cartridge can be fitted with the M524-series, M526-series, M567, or M532 fuzes. The M821A2/821A1/889A1 consists of the following major components: M935 Point Detonating Fuze or M734/734A1 Multi-Option Fuze. The cartridge is painted light green with black markings and one narrow brown band. 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. Fired . He must ensure that the ball-shaped end of the locking rod is secured in its recess by the locking latch. The fuze wrench, M18, assembles the fuze to the cartridge, and the bladed tip on the end sets PD-type fuzes. The cartridge weighs about 9.12 pounds. b. As soon as the sight data are announced, the gunner places it on the sight, lays the mortar for elevation, and traverses onto the aiming post by turning the traversing handwheel and adjusting nut in the same direction. 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. Figure 4-8. If water is not available, the gunner must stand clear of the mortar until the barrel is cool. The propellant train (except the training cartridge) consists of an ignition cartridge and propellant charges. A proximity fuze is an electronic device that detonates a projectile by means of radio waves sent out from a small radio set in the nose of the projectile. a. 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. The vertical cross line of the sight is on the left edge of the aiming point. .50: BROWNING, M2 (HEAVY BARREL, TURRET TYPE) ON MOUNT, MACHINE GUN, TRAILER MTD: MULTIPLE CAL. b. The superior flow characteristics of these BALL POWDER . b. The fuze body is graduated from 0 to 50 seconds in 2-second intervals; 10-second intervals are indicated by bosses. 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). He makes large deflection shifts by shifting the bipod assembly and keeps the bubbles level during firing. The term "indirect fire" means firing at an enemy without having a. Referring and realigning aiming posts ensure that all mortars are set on the same data. The M252 81 mm medium weight mortar is a British-designed smooth bore, muzzle-loading, high-angle-of-fire weapon used for long-range indirect fire support to light infantry, air assault, and airborne units across the entire front of a battalion zone of influence. If the primer is not dented, the round may be used again. He rotates the socket so that the open end is pointing in the direction of fire. M252 81mm Mortars The M252 81mm medium extended range mortar (see diagram below) is a crew-served, smooth bore, muzzle loaded, high angle of fire weapon system. 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. He then checks the sight picture to ensure he is within 20 mils of a proper sight picture. The fuze threads and fuze well threads are inspected for damage. (3) Markings on rounds. mortar, 81-mm: m29a1 and m29; firing cartridge, he, m374a2 and m374; cartridge, wp, m375a2 and m375 (s&i by prop see details, footnotes) ardec: ft 81-al-4(abr) active: 12/24/1970: firing tables for mortar, 81mm, m29 and m1 firing cartridge, illuminating, m301a3 with fuze, time, m84a1, height of burst, 600 meters (s&i by prop see details . A lock ( The cartridges are painted olive drab with yellow markings. The safety pull wire is removed just before inserting the cartridge into the mortar. Weights (pounds) System (including basic issue items) Barrel (with blast attenuator device) Mount M3A1 Baseplate The round has a burst height of 600 meters and provides illumination for about 60 seconds for an area of about 1,200 meters. Both the M90 and M90A1 propellants are in nine wax-tested, cotton cloth, bag increments assembled to the tail unit.