Recoilless Rifle

Explosive Components:

Detonator M47 and Relay M7.

References:

TM 9-1300-251-20 SC 1340/98-IL

Ammunition 105mm Recoilless Rifle
Type Classification:

LP AMCTC 8269 dtd 1971.

Use:

Mechanical time fuzes of the M563 series are used to function flechette-loaded 105mm Cartridge M546.

Description:

Mechanical Time M563 series fuzes are comprised of a solid aluminum head, a lower cap assembly with time graduation in seconds which houses a setting pin and hammer spring, a fuze body which contains the clockwork timing mechanism, the muzzle action feature, the-detonator-holder plug assembly and the vernier scale for accurate time settings to a tenth of a second. The lower cap time graduations contain an MA designation for muzzle action, a 1/2 second setting for minimum downrange functioning, and whole-second increments for pre set downrange functioning. The vernier scale for fractional-second time settings and reference zero-line time indication are contained on exterior of the body. Detonator M47 is positioned directly under the timing movement firing pin. The detonator holding plug assembly contains Detonator M87 centrally located below Relay M11 positioned in the closing plug. Between Relay M11 and Detonator M87 two overlapping centrifugally operated weights provide safety in handling.

Functioning:

When the fuze is set, turning the lower cap rotates the timing disk proportionately by means of the setting pin, engaged in an upraised lug on the disk. Upon firing, setback forces the hammer spring to strike the upraised lug, releasing the timing disk from the setting pin. As projectile spin rate increases, centrifugal force releases the detents securing the timing movement, and the timing disk begins to turn. At the same time, centrifugal force causes the safety weights in the base of the fuze to move aside to clear the detonation path between Relay M11 and Detonator M87. When the disk has rotated for the preset time, the notch in the disk releases the firing arm. The firing arm turns, moving the firing arm safety plate so that the firing pin strikes Detonator M47 to initiate the explosive train to the projectile. If muzzle action was selected, the fuze will function immediately as the projectile leaves the muzzle. This is accomplished by the combination of angular acceleration and setback forces releasing the alpha weights or setback pins depending on the fuze used, which in turn, releases the centrifugal weights exposing the notch in the timing disk activating the firing pin sequence for functioning of the M47 detonator and initiation of the fuze explosive train. If another range was set, fuze function will occur so as to result in optimum flechette dispersion for the range; for setting between 200 and 500 meters, the fuze will function 100 meters short of the range set. For longer range settings up to 4400 meters, functioning will occur 75 meters short of the range set.

Difference Between Models:

Fuze XM563E1 has a larger timing disk than Fuze XM563E2. The muzzle action feature in Fuzes XM563E1 and XM563E2 is activated by four alpha weights and two centrifugal weights. In Fuzes XM563E3 and XM563E4, the alpha weights are replaced by four setback pins. The M563 (XM563E4) differs from the XM563E3 in the escapement mechanism in which an improved configuration of balance lever and spring is used.

Tabulated Data:

Length:

Assembly Dwg. No.

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