Section Iii Launcher Controls And Sighting Equipment

11. Trigger a. The trigger is located in front of the trigger grip (fig. 30). It is made of aluminum.

b. Some rocket launchers M20 are equipped with electric firing mechanism C7313326 (single action-fig. 7). After the trigger of this mechanism is squeezed a spring returns it to its normal position when the trigger is released. The movement of the trigger, when it is squeezed and released, rocks the armature of a magneto firing mechanism which is housed in the trigger grip. The rocker arm and armature provide snap action to the movement of the armature.

Firing Button

SAFETY SWITCH

FIRING MECHANISM—C7313326 (SINGLE ACTION)

SAFETY BUTTON

FIRING MECHANISM—E7140325. {DOUBLE ACTION)

RA PD 118077

f.. Some rocket launchers M20 and rocket launchers M20B1 are equipped with electric tiring mechanism B7140325. In this mechanism also, the return of the trigger to its normal (forward) position is accomplished by spring action after it has been squeezed and released. This mechanism not only imparts snap action to the rocking of the armature in the magneto coil but produces a complete cycle of the armature, by sign action, when the trigger is squeezed. The return motion of the trigger when it is released does not generate any electric current.

d. In both firing mechanisms movement, of the magneto armature generates electric current which is used to ignite the rocket (see pars. 47-49).

12. Safety a. Some launchers M20 are equipped with firing mechanism C731326 single action-fig. 7) and are each provided with a safety switch.

(1) The safety switch is located on the rear of the trigger grip (fig. 7) where it is handy for manipulation by the thumb of the right, hand. The safety switch button is brass.

(2) The safety switch has two positions. The upper position is its "SAFEV position. In this position the switch functions to shunt (short circuit) the current and so prevent it from reaching the igniter of the rocket. The lower position of the safety switch is its "FIRE" position. In this position the switch functions to open the shunt permitting the current to reach the igniter of the rocket. Markings on the left grip (fig. 7) indicate the two positions of the safety switch (pars. 47^9).

b. Some launchers M20 and launchers M20B1 are equipped with firing mechanism B7140325 (double action-fig. 7) which is provided with a safety button.

(1) The safety button, is located in a slot in the left grip (figs. 7 and 29 where it is handy for manipulation by the thumb of the right hand. The safety button is aluminum.

(2) The safety button has two positions. The lower position is its "SAFE'* position. In this position the block of the safety mechanism is interposed behind a protruding lug of the trigger and locks the trigger. The upper position of the safety button is its "FIRE" position. In this position the block of the safety mechanism is held clear of the lug on the trigger and the trigger is free to move.

Caution: Whenever firing is not being attempted, the safety must be kept in its "SAFE" position.

13. Barrel Coupling Lock Lever a. The barrel coupling lock lever is located 011 the right side of the rear barrel assembly just behind the barrel coupling nut (figs. 18 and 20). It is made of steel.

b. The barrel coupling lock lever is used to release the barrel coupling lock and must be operated when assembling the front and rear barrel assemblies into firing position (par. 21) and when breaking (he weapon into carrying position (par. 25). It is operated by raising and holding the lever in its unlocked position. When the lever is released, a spring returns it to its locked position.

14. Barrel Latch Handle a. The barrel latch handle is located 011 the right side of the rear barrel assembly just back of the trigger grip (figs. 18 and 20). The handle is aluminum.

b. The barrel latch handle is used to release the barrel latch which locks the front and rear barrel assemblies in carrying position. Moving the handle forward retracts the barrel latch bolt causing it, to release the barrel latch strike (on the front barrel assembly). Two springs on the barrel latch bolt (fig. 26) keep the bolt in its normal extended position. When the barrel hook of the front barrel assembly is engaged in the barrel eye of the rear barrel assembly and the'barrels are pressed together, the bolt latches the strike. This fastens the barrels together in carrying position, and the barrel latch handle must be pressed forward to release the latch in order to separate the barrels (par. 25).

Xote.—Such parts as the barrel hoolt and eye and the barrel strike occur as parts only in the M20 launcher. Iu the M20B1 launcher, the functions of these parts are effected by shapes cast integral with the barrels.

15. Monopod Sleeve Body a. The monopod sleeve body is the cylindrical, knurled part of the monopod (figs. 18 and20).

b. The monopod sleeve body is used to adjust the height of the monopod. Clockwise rotation of the sleeve body, as viewed from the bottom, extends the monopod, and vice versa (par. 21/;). When the launcher stands on the bipod and monopod, adjustment of the height of the monopod is a stable means of controlling elevation of the weapon (sec. VIII, ch. 3).

16. Bipod Trip a. The bipod trip is located at the bipod front ring (figs. 16 and 17). It is made of aluminum. The leg lock buttons of the bipod front ring assembly act as detents (o hold the bipod in folded position against the front barrel.

The bipod trip serves to pry the bipod legs free of the lock buttons for unfolding. Pulling the trip away from the barrel pries the bipod legs free. "PULL" is marked on the trip to indicate this operation (par. 21& (1)).

c. Two springs 011 the trip pin hold the trip in its normal position, flat against the barrel (par. 46/).

17. Bipod Slide Catch a. The bipod slide is mounted on the front and rear rings of the bipod assembly. The slide block moves along the slide as the bipod is folded and unfolded. The bipod slide block catch is pivoted on the under side of the slide block and engages either ratchet teeth or notches on the underside of the slide (fig. 8). The slide and slide block catch are made of steel.

b. The bipod slide block catch of some M20 launchers is released by pressing the.lever end of the catch up against the slide block. The catch then swings free of the rat chet teeth or notches on the slide. A spring on the catch pivot, pin keeps the catch pressed against the slide.

c. The bipod slide block catch, of some M20 launchers and of M20B1 launchers, may also be released by pulling the catch down out of engagement with the ratchet or notches 011 the underside of the slide, as well as by pressing the lever end of the catch up against the slide block as described in b above. A spring 011 the catch pivot pin keeps the catch pressed against the slide.

d. The slide block catch must be released to permit folding the bipod but the ratchet or notches permit unfolding of the bipod without touching the catch. By engaging the ratchet or notches of the slide, the slide block catch will hold the bipod against folding in any position to which the bipod is extended.

18. Bipod Rear Ring Lock Handle a. The rear ring lock handles of all the 3.5-inch rocket launchers M20 and M20B1 are operated in similar fashion although the design has been modified. On M20 launchers of early manufacture the bipod rear ring lock handle is located at the top of the bipod rear ring (fig. 23) (directly opposite the slide). On M20 launchers of later manufacture and on M20B1 launchers the bipod rear ring lock handle is located on the left side near the top of the rear ring (fig. 24).

b. To release the bipod rear ring lock, raise the lock handle. To lock the position of the barrel in the bipod rings, press the handle down against the bipod rear ring.

M20 Rocket
BIPOD SLIDE

SLIDE BLOCK CATCH

-FRONT BARREL HOOK

3.5-INCH ROCKET LAUNCHER M20 (OF EARLY MANUFACTURE)

SLIDE BLOCK CATCH

RA PD 118080

3.5-INCH ROCKET LAUNCHER M20B1

Figure S. Front barrel bipod folded.

c. The roar ring lock handle releases the rear ring lock so that, the front barrel can be rotated in the bipod rings. When the weapon stands on its bipod and monopod, uneven ground may tilt the bipod and to prevent tilt of (he bipod from affecting the sighting of (lie weapon the rear ring lock is released and the barrel rotated in the bipod rings to bring the monopod exactly vertical as gaged by eve. The bipod rear ring is located in this position. Slops on the barrel prevent longitudinal motion of the barrel in the bipod rings when the lock is released (par. 2\b (2)).

19. Contactor Latch Housing Assembly a. The contactor latch clamp encircles (he rear barrel of M20 launchers just forward of the breech guard. The contract or latch housing assembly of M20 launchers pivots on this clamp. The contactor latch housing assembly of M20B1 launchers pivots on lugs cast integral with the rear barrel. The contactor latch plate protrudes through an opening in the breech guard (fig. 28). Except for the brass shunt, the contactor latch housing assembly is made of steel.

b. A steel blade, riveted to the rear of the body of the contactor latch housing assembly, engages notches in the radial fins at I he rear of the rocket and serves to hold the rocket in its proper firing position in the launcher. The contact between the blade of the contactor latch and the rocket fins provides grounding of the rocket to the rear barrel for the completion of the firing circuit. A spring keeps the rear end of the contactor latch housing assembly depressed.

c. When the forward end of the contactor latch housing assembly is pressed down against the barrel, the blade at the rear of the housing assembly swings clear of the breech of the launcher tube. This is done during loading or unloading of the launcher (pars. 21 c (5) and 23).

20. Sighting Equipment

The sighting equipment of M20 launchers is supported on a bracket which appears on the left side of the rear barrel just forward of the monopod. The reflecting sight assembly pivots in a bushing of the sight bracket assembly. An elevation plate is mounted on the sight bracket (sec. IX. ch. 3). The support of the sighting equipment of M20B1 launchers is similarly located but is cast integral with the rear barrel.

a. Range Scale.

(1) The range scale is on the elevation plate and each weapon is equipped with either one of two elevation plates. The elevation plate must correspond to the reticle of the reflecting sight assembly used. Weapons equipped with reflecting sight assemblies D7313440 (concentric circle-fig. 37) or D7 1 6285)0 (oval-fig. 38) use elevation plate C7138366 (fig. 35). Weapons equipped with reflecting sight assembly D7141999 (ladder type reticle-fig. 39) use elevation plate C7141998 (fig. 34).

(2) The range scale on elevation plate C7138366 (fig. 35) is calibrated from 0 to 9 and indicates the range in hundreds of yards. A notch on the elevation plate for each fifty yards of range is engaged by a projection on the indicator arm pointer as it sweeps over the elevation plate when the indicator arm and reflecting sight are swung on the pivot in the sight support. These notches serve as detents to hold the range setting of the sight.

(3) The range scale on elevation plate 07141998 (fig. 34) is calibrated from 0 to 9 but there are no calibrations between 0 and 5. The figures on the elevation plate indicate the range in hundreds of yards. Calibrations are not needed between 0 and 5 on the elevation plate because a range up to 450 yards is covered by the reticle pattern. Between 5 and 9 on the range scale there is a notch on the elevation plate for each 50 yards of range. These notches are engaged by a projection on the indicator arm pointer as it sweeps over the elevation plate when the indicator arm and reflecting sight are swung on the pivot in the sight support. These notches serve as detents to hold the range setting of the sight.

(4) To set the sight to a specific range, move the indicator arm to the position on the elevation plate corresponding to the desired range. For example: If the range is estimated as 600 yards, set the indicator arm pointer at "6" on the elevation plate.

b. Graduations on Indicator Arm Yoke. The reflecting sight lens frame is secured to the indicating arm yoke by a hinge stud which permits the sight to be folded back out of the way against the launcher rear barrel when not in use (figs. 34 and 35) or to be swung out into the extended position (fig. 36) for use in firing. The head of the hinge stud carries an index mark which is set against the adjacent scale on the indicator arm yoke when setting the sight in azimuth during boresighting (par. 56ft). The five graduations on the indicator arm yoke, spaced 15° apart, are for reference only.

c. Manipulation of Sight.

(1) The sight is unfolded from its carrying position by pulling it out away from the barrel, causing it to pivot on the sight hinge stud in the yoke of the indicator arm. It is swung out until the ball detent of the sight hinge stud engages and holds the sight in its firing (sighting) position.

(2) The delent. functions to hold the sight, in both its currying and firing (sighting) posit ions.

(3) After use, the sight is swung back out of the way (for carrying) by pushing it back against the barrel until the detent snaps and secures the sight in carrying position.

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  • sm
    Where can i get a launcher grip pointer?
    8 years ago
  • Malva
    How to operate a m20b1?
    7 years ago

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