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MIL-C-45978A (AR)
6.2). No first article requirements shall be waived without
review and approval by the Procuring Contracting Officer (see
6.2).
.
3.2.1 First Artitle - Init ial Pr oduction Testlna (FA-IPTI
The requirements for First Article - Initial
Requirement~
Production Testing are collected and included in Appendix A.
When specified, these FA-IPT requirements are mandatory for
compliance (see 6.2) .
.
The cannon shall perform the
nc tional chara cteristic~
3.3
firing, pressure sustaining, and projectile launching functions
of the Howitzer, Light, Towed 105MM:M204. The breech mechanism,
firing mechanism, and other moving parts shall function smoothly
without interference, erratic movement or malfunction.
3.3.1 Br eech mechanism. When the operating lever is unlatched
and rotated clockwise (rearward) , it shall rotate the crank
clockwise. The rotation of the operating lever shall cock the
firing mechanism and cause the horizontally sliding breechblock
to move to the right, and open the breech. The extractor shall
eject the empty cartridge case from the breech chamber. When the
operating lever is rotated counterclockwise, the breechblock
q
shall move to the left, and close the breech.
3.3.2 Firing mechanism group. During the first thirty-five
degrees clockwise rotation of the operating lever, the crank
shall rotate the retractor cam counterclockwise. The rotation of
the retractor cam shall cause the retractor to force the firing
pin rearward past the sear and the firing pin spring shall
compress. Rearward movement of the firing plunger shall pivot
the trigger and the sear, which shall rotate and release the
firing pin. The rotation of the sear and release of the firing
pin shall cause the firing pin spring to expand and drive the
firing pin forward to strike and fire the cartridge primer.
The firing plunger reset
3.3.2.1 Firing p lunger reset position
position is an indication of the distance that the firing plunger
is caromed forward as the breech mechanism is opened. This
position shall be measured as the minimum recessed distance from
the front face of the breech ring to the front end of the firing
plunger. This distance shall be not less than 0.055 inch nor
more than 0.110 inch.
The firing plunger fire
3.3.2.2 firing pl unger fire pOSitiOn
q
q
position is an indication of the location of the firing plunger
just as the firing pin is released by the sear (breech mechanism
closed) . This position shall be measured as the recessed
distance from the front face of the breech ring to the front end
of the firing plunger. This distance shall be not less than
4
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