4.5.3 Trigger pull test. Machine guns shall be tested for
trigger pull requirement (see 3.4.3) using the inspection
The machine gun
equipment in accordance with drawing 11603790.
shall be cocked and the safety shall be in the "fire" position to
pull the trigger and disengage the sear from the operating rod.
The loads shall then be gradually applied to the trigger in the
direction specified on the applicable drawing. When the minimum
load is applied, the sear shall not be disengaged from the
operating rod and when the maximum load is applied, the sear
The trigger pull
shall be disengaged from the operating rod.
shall also be tested for creep by applying pressure manually to
the trigger at a uniform rate of increase over a period of not
less than 3 seconds.
4.5.4 High pressure resistance test. Machine guns shall be
tested by firing one high-pressure test cartridge (see
Machine guns shall be tested using the firing
fixture conforming to drawings 7273925 and 11703783.
assembly shall have been proof fired and magnetic particle
inspected in accordance with the applicable drawing and other
Bolts and barrel assemblies to be
assembled into production machine guns shall be proof fired only
as part of the completed machine guns and magnetic particle
inspected and marked in accordance with the applicable drawing
and other applicable documents. Bolts and barrel assemblies to
be used as repair parts shall be proof fired independently of the
production machine gun and magnetic particle inspected and marked
in accordance with the applicable drawings and other applicable
After proof firing, machine guns shall be examined
for cracks, deformations, and other evidence of damage, and
cartridge cases visually examined for bulges, splits, rings and
A 1/8 inch high
other defects caused by defective barrels.
letter "P" shall be applied to the receiver adjacent to and in
line with the area allocated for the Department of Defense
complete inspection approval stamp indicated on drawing 11699750
on machine guns that have passed this test.
220.127.116.11 Firing schedule. Machine guns shall be bested for
functioning requirement (see 3.4.5) in accordance with the
schedule specified in Table II. The machine guns shall be tested
using the firing fixture conforming to drawing 7273925.
first 500 machine guns, the ammunition shall be linked together
in 100-round belts with a dummy cartridge separating each 50
The belts of ammunition shall hang unsup-
rounds (see 18.104.22.168).
ported vertically from the firing fixture feed tray for a