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. Cartridges assembled with the M524 (A1, A2, A3, or A4) fuze are for use by the US Marine Corps and US Navy only. Official websites use .mil It uses the M205 propelling charge, consisting of four horseshoe-shaped increments fitted around the tail. The fuze has a safety wire that must be removed before firing. Red phosphorus rounds can be fired from the M29/M29A1 at a reduced charge (maximum charge = charge 2). (1) The M772A1 fuze is a MTSQ. 4-10. The assistant gunner attempts to maintain the traversing mechanism on a horizontal plane. d. The first ammunition bearer stands to the right rear of the mortar. An 81 mm mortar is a medium-weight mortar. The fuze is set manually to proximity, point detonate, or delay modes. PDF 81-mm MORTAR, M252 - GlobalSecurity.org 107 Army Pentagon The M252 is highly accurate up to ranges of 4500m to 5700m depending on the Remaining increments are repositioned towards the rear of the tail fin assembly when firing the cartridge with horseshoe-shaped increments at less than full charge. The ignition cartridge strikes the firing pin and detonates, which causes a flash that passes through the radial holes in the shaft. The cartridge is painted olive drab with yellow markings. M120/M121 120 mm Mortar. The M532 fuze is a radio doppler fuze that has a proximity (PROX) or SQ/IMP function. g. The barrel clamps can be moved along the barrel to counter large changes in elevation. d. The gunner recovers the baseplate to the area designated by the squad leader. When set at SQ, the fuze functions on point impact or graze contact. They use the M5 propelling charge that consists of eight cloth bags attached to the tail unit. h. Where the ground is uneven and there is no level surface for the bipod, the gunner can adjust the plain leg. The vertical cross line of the sight is on the left edge of the aiming point. It is fitted with a safety wire and pin that are removed immediately before firing. (4) The bipod locking latch is locked, securing the barrel clamps. The ignition cartridge (with primer) is fitted into the base of the fin shaft. To convert the fuze from PROX to SQ/IMP, the top of the fuze must be rotated 120 degrees (one-third turn) in either direction. PDF Introduction to Crew Served Weapons B3m4078 Student Handout 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 . Powered by Hugo. The fuze wrench, M18, assembles the fuze to the cartridge, and the bladed tip on the end sets PD-type fuzes. When targets are beyond such irregularities, a clearance of at least 30 meters should be allowed to ensure maximum effect over the target area. These are NDI items . If water is not available, the gunner must stand clear of the mortar until the barrel is cool. In addition to loading, he swabs the bore after 10 rounds have been fired or after each fire mission. He indicates the initial direction of fire by pointing in that direction and commands ACTION. The gunner removes the sight and places it in the case with 3200 deflection and 0800 elevation indexed. The M29 would become the standard American mortar in the upcoming Vietnam War. Check the post SOP before applying the following procedure: (1) Select a place at least 100 meters from the mortar position, parked vehicles, and ammunition piles. e. The M362A1 and M362 HE cartridges are of steel forge construction and contain about 2.10 pounds of composition B explosive. When cartridges have been prepared for firing, but are not used, all powder increments and safety wires are replaced. XM1210. Indirect Fire Mount, M177, in folded position. It has no safety pins or wires to reduce preparation time. b. FM 23-90 Chptr 4 81-mm Mortar, M252 - GlobalSecurity.org (5) With the exception of a few unused increments (within the same ammunition lot number) as replacements for defective increments, excess powder should be removed from the mortar position. Illuminating is used for battlefield illumination and signaling. (703) 614-3727, Office of the Chief Information Officer (5) Four inches of elevation shaft are exposed, and the shaft is not bent. (3) The securing strap is correctly located, securing the barrel clamps and buffers to the plain leg. a. Red phosphorus/white phosphorus--M819 and M375-series. The table on the right describes the three most common setups. It is a 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. He exposes 4 inches (100 millimeters) of elevation shaft and folds the handle. 0.50, BROWNING, M2; FIRING CARTRIDGE, ARMOR-PIERCING-INCENDIARY, CAL. b. Figure 4-7. The leg-locking handwheel must then be tightened by hand, ensuring the teeth on either side are correctly meshed. f. Installation. The assistant gunner carries the bipod to the front of the barrel and places the bipod feet on the ground 12 to 15 inches in front of the baseplate and astride the line of fire. The fuze arms and functions normally when fired at any angle of elevation between 0800 and 1406 mils at charges 1 through 9. c. The first ammunition bearer ensures that each cartridge is clean, the safety pin is present, and the ignition cartridge is in good condition. M252 81mm Medium Extended Range Mortar - Specifications The gunner is given an administrative command to lay the mortar on a deflection of 2860 or 2740 mils. This round may be stored in a horizontal position. He maintains the ammunition for firing and provides local security for the mortar position. All rounds are colored according to their type. Mount The cartridge weighs about 9.4 pounds. The M374A2 and M374A1 cartridges are fitted with the M90A1 propelling charge. 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 places firing data on the sight and lays the mortar for deflection and elevation. c. The M374A3 HE cartridge is constructed from pearlitic malleable cast iron and contains about 2.10 pounds of composition B explosive. Types of rounds, classification, and characteristics for the 81-mm mortar, M29A1 (Standard B for the 81-mm mortar, M252). The tabulated data of the 81-mm mortar, M252, are shown in Table 4-1. [1] [2] Many countries use or used an 81 mm mortar in their armed forces. The M1 became the standard American . Barrel (with blast attenuator device) They should not be approached for 5 minutes or disturbed for at least 30 minutes after firing. The fuze threads and fuze well threads are inspected for damage. Both the M90 and M90A1 propellants are in nine wax-tested, cotton cloth, bag increments assembled to the tail unit. After the rounds have been removed, they should always be handled with two hands to prevent accidental dropping. If it gets wet or dirty, it must be wiped off at once. The M252 81mm medium extended range mortar (see diagram below) is a crew-served, smooth bore, muzzle loaded, high angle of fire weapon system. He ensures that the firing pin recess is facing upwards. (8) To help minimize the occurrence of short rounds and or duds, unpackaged ammunition that has been dropped should not be fired. When fired, the cartridge carries the ignition cartridge with it, leaving the mortar ready for the next cartridge. The aluminum tail assembly has six integral fins equally spaced around the rear, which stabilize the round in flight. To make the shift, the gunner places the fingers of his right hand in the muzzle and his left hand on the left leg. 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. He makes large deflection shifts by shifting the bipod assembly and keeps the bubbles level during firing. In the U.S. Army and U.S. Marine Corps, it is normally deployed in the mortar platoon of an infantry battalion. No tools are needed to set the fuze, and the setting can be changed several times without damaging the fuze. Army Publishing Directorate - Firing Tables (2) The fin and fuze assembly must be checked for tightness and damage. d. Multioption. 4-4. Both legs are fitted with a disk-shaped foot with a spike beneath to prevent the mount from slipping. It is designed to be fired in the indirect fire mode, cannot be fired handheld, and norm ally utilizes a FDC. The following safety checks must be enforced before firing the mortar. TM - Technical Manuals (Range 9) TM - Technical Manuals (Range 10) TM - Technical Manuals (Range 11-4) TM - Technical Manuals (Range 11-5) . They contain about 2.10 pounds of composition B explosive. He then checks the sight picture to ensure he is within 20 mils of a proper sight picture. Table 4-2. 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 company level vehicles also carry a vehicle-mounted 120mm mortar, which is augmented by the 60mm M224 mortar for dismounted use. From introduction up to halfway World War 2 the ML 3-inch had a poor range of up to 1.45 km. M327 mortar is an extended range mortar system operated by Marine Corps Artillery Units. It is especially useful if the baseplate sinks deep into the ground during prolonged firing. He moves the mortar until the vertical line of the sight is aligned approximately on the aiming post. Each round is stenciled with the ammunition lot number, type of round, type of filler, and caliber. The gunner can depress the barrel, if necessary, to provide easier access to the firing pin. e. The squad leader picks up the aiming posts and sight. Safety before firing is provided by a safety wire, which must be removed just before firing. Tabulated data. If he is not within 20 mils, the gunner and assistant gunner must make another large shift before moving on. There is a selector on the lower shaft for non-delay or delay impact action. c. The M375A2, M375A1, and M375 cartridges may also be used. General Dynamics Ordnance and Tactical Systems is the leading manufacturer of propellants for 60mm, 81mm and 120mm Mortar Systems. b. However, since explosives are affected by moisture and high temperature, they must be protected. Short cartridges can be expected when firing below charge 4. The M853 cartridge (M252 only) has a cylindrical body that contains an illuminating candle and parachute assembly. 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, HE, M795 PROJECTILE, HE, M795 IM PROJECTILE, HE, M1122 PROJECTILE, IR ILLUMINATING, M1123 PROJECTILE, ILLUMINATING, M1124 INCLUDES FIRING TABLES FOR PROPELLANTS: M119A2 (CHARGE 7R), M203A1 (CHARGE 8S), AND MODULAR ARTILLERY CHARGE SYSTEM (MACS) PROPELLANTS: M231 (CHARGES 1L AND 2L), M232 AND M232A1 (CHARGES 3H, 4H AND 5H) (S&I BY PROP SEE DETAILS, FOOTNOTES) . (6) The primer cartridge is checked for damage or dampness. 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. The floating firing pin located within the primer has approximately 1/16 of an inch to move around. (2) Burn all dead grass or brush within 30 meters around the burning place. e. Dummy. 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.
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