During firing, the breech plug on the barrel is sealed and locked to the rotatable socket in the baseplate. b. He lays for deflection, taking the proper sight picture. Proximity (VT). This action breaks an internal sheet pin and internal wire, thereby disabling the proximity function. If the mortar section is to operate quickly and effectively in accomplishing its mission, mortar squad members must be proficient in individually assigned duties. a. b. If water is not available, the gunner must stand clear of the mortar until the barrel is cool. The tabulated data of the 81-mm mortar, M252, are shown in Table 4-1. b. 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. Then it is removed from the bipod and laid horizontally on the ground at the dud pit until it can be turned over to ordnance personnel. He then checks the sight picture to ensure he is within 20 mils of a proper sight picture. The assistant gunner checks the bipod and ensures that--. System (including basic issue items) Secure .mil websites use HTTPS When a large number of cartridges are needed for a mission, they may be removed from the containers and prepared. OPERATOR`S MANUAL FOR MORTAR, 81-MM, M252 (NSN 1015-01-164-6651) (EIC 4SK){TM . Figure 4-4. The cartridge weighs about 9.4 pounds. Close approach to crests, trees, towers, large buildings, parked aircraft, mechanized equipment, and similar irregularities causes functioning at heights greater than average level. d. The gunner rough levels the cross-level bubble by making the bubble bounce from one side to the other. It weighs about 9.05 pounds. The propelling charge consists of an ignition cartridge and removable propellant increments. The first ammunition bearer puts both hands on the cooling fins under the barrel and slowly lifts the barrel until it is horizontal. a. Before-firing checks include the following: (1) Ammunition should be free of moisture, rust, and dirt. It uses the M219 propelling charge and weighs about 9.1 pounds. 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) . Short cartridges can be expected when firing below charge 4. It arms within a maximum of 2.50 seconds. They are painted light green with red markings and one narrow yellow band. FT 81-AI-3 Firing Tables Mortar, 81mm: M28A1 and M29 Mortar 81mm Self propelled M125A1 and M125 Carrier, 81mm Mortar Tracked XM755 (1) Marking on container. In addition to loading, he swabs the bore after 10 rounds have been fired or after each fire mission. The mortar is within two turns of center of traverse. (4) The bipod locking latch is locked, securing the barrel clamps. The enemy will use them. This ensures a maximum traversing and elevating capability after making the movement. (2) Burn all dead grass or brush within 30 meters around the burning place. (See FM 7-90 for a discussion of the duties of the platoon headquarters.). It is light enough to be portable when broken down into. Upon completion of any bipod movement on the barrel, the gunner ensures that the firing pin recess is facing upward. The cartridge uses the M205 propelling charge and is assembled with the M567 or M524-series fuze. An internal clock mechanism provides nine seconds of safe air travel (610 to 2,340 meters along trajectory for charge 0 through 9, respectively). .50 MACHINE GUN, M3; FIRING CARTRIDGE, CAL. The M252 system . If, upon removal of the safety wire, a buzzing sound in the fuze is heard, the round should not be used. It provides illumination for about 60 seconds with 600,000 candlepower illumination. 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. When set at delay, the fuze train causes a 0.05-second delay before functioning. Standard A ammunition for the M29A1 mortar is Standard B for the M252 mortar (, Light green Yellow band with red markings. He uses the chain of command to assist him in effecting his command and supervising duties. d. The gunner recovers the baseplate to the area designated by the squad leader. 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. The 60mm mortar section is located in the weapons platoon of the rifle company, is armed with three 60mm mortars, and is The 81-mm mortar, M252, is a smooth-bore, muzzle-loaded, high-angle-of-fire weapon. An ammunition lot number is assigned to each ammunition lot, which is marked on each cartridge and packing container. The components of the mortar consist of a canon, sight, mount, and baseplate. When the approximate alignment is completed, the gunner signals the assistant gunner to lower the bipod by pushing down on the mortar. The aluminum tail assembly has six integral fins equally spaced around the rear, which stabilize the round in flight. ), 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, XM776 ON HOWITZER, MEDIUM, TOWED, 155MM, XM777 FIRING PROJECTILE, HE, M795 (S&I BY PROP SEE DETAILS, FOOTNOTES), FIRING TABLES FOR 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, SMOKE, WP, M1121 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 FOOTNOTES). Several types of RP/WP ammunition are described herein. Before the mortar is mounted, the squad must perform premount checks. f. The open end of the socket must continue to point in the direction of fire. (d) Firing is slowed if mask clearance must be checked before each firing but this can be eliminated if minimum mask clearance is determined. If not, he may still fire at the desired range by selecting a charge zone having a higher elevation. MFCS Dismounted. These cartridges are used first in subsequent firing so that once-opened stocks can be kept to a minimum. Red phosphorus cartridges (M252 only) are stored the same as HE cartridges. (3) The M84A1 fuze is a single-purpose, tungsten-ring, mechanical-time fuze used with the 81-mm M301A3 illumination cartridge. Short cartridges can be expected when firing below charge 4. .30, BROWNING, M1919A4 AND M2 (HEAVY BARREL), .30, M2 (REPRINTED W/BASIC INCL C1) (S&I BY PROP SEE DETAILS, FOOTNOTES), GUN, MACHINE: CAL. Complete cartridges are always handled with care. He may assist the gunner in shifting the mortar when the gunner is making large deflection changes. These fuzes use a clockwork mechanism to delay functioning for a specific time. 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. The M374 cartridge is fitted with the M90 propelling charge. Examples are: 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). 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. Training practice is used only for training. The safety wire must be removed before firing. The ignition cartridge (with primer) is fitted into the base of the fin shaft. The safety pull wire is removed just before inserting the cartridge into the mortar. The M29 would become the standard American mortar in the upcoming Vietnam War. It was even a tool used by airborne units, and was dropped in parachute bundles during Operations Neptune, Market Garden, and Varsity. (b) In selecting the exact mortar position, the leader looks quickly for mask clearance and overhead interference. 60MM M224A1. The mount consists of elevating and traversing mechanisms and a bipod (Figure 4-4). (1) The rotating socket is free to move in a complete circle. One-quarter turn on the adjusting nut equals one turn of the traversing handwheel. c. Crest Clearance. d. The ammunition is protected from mud, sand, dirt, and water. The assistant gunner exposes 8 inches (200 millimeters) of elevation shaft, leaving the elevation handwheel unfolded. Tabulated data. 4-4. If the primer of the ignition cartridge is dented, the first ammunition bearer attempts to replace the safety wire and places the round in a marked, safe location for disposal by ordnance personnel. The M1 became the standard American . .50: AP, M2 AND CARTRIDGE, CAL. I say 120s are bad because they suffer from terrible dispersion even when not shooting at 6km. The barrel clamps are then closed. M3A1 Baseplate He exposes 4 inches (100 millimeters) of elevation shaft and folds the handle. Official websites use .mil (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. *FREE* shipping on qualifying offers. The components of the mortar consist of a cannon, mount, and baseplate. 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. 60mm, 81mm, and 120mmMortar Increments. c. The first ammunition bearer ensures that each cartridge is clean, the safety pin is present, and the ignition cartridge is in good condition. This may preclude moving the bipod. 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. c. The M375A2, M375A1, and M375 cartridges may also be used. The gunner places the announced deflection on the sight (without disturbing the lay of the weapon) and looks through the sightunit. Army Publishing Directorate 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 cartridge is painted olive drab with yellow markings and weighs about 9.05 pounds. The muzzle end has a short tapered lead-in which acts as a . When cartridges have been prepared for firing, but are not used, all powder increments and safety wires are replaced. When the gunner is satisfied with his sight picture he announces, "Up.". a. M64A1 Sightunit. In charge was the platoon commander - normally a lieutenant.