4.5.3 Trigger pull test. Machine guns shall be tested for
trigger pull requirement (see 3.4.3) using the inspection
equipment in accordance with drawing 7796424. The machine gun
shall be cocked and the safety shall be in the "fire" position.
The loads shall then be gradually applied to the trigger in the
direction specified on the applicable drawing. The trigger pull
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. Fire on M60 High
Pressure Test Cartridge in every barrel assembly (7269028), tube
assembly (7269042), and bolt (11010358). After firing) apply
magnetic particle inspection to these parts. After firing,
examine these components for cracks, deformations, and other
evidence of damage. After firing, examine cartridge cases from
the barrel assemblies and tube assmblies for bulges, splits,
rings and other indications of defective barrels. Determine that
specific scratches and marks, if present in the chamber which
meets surface texture requirements, have not caused marks on the
cartridge cases (see 188.8.131.52.1).
4.5.5 Functioning firing test.
184.108.40.206 Firing schedule. Machine guns shall be tested for
functioning requirement (see 3.4.5) in accordance with the
schedule specified in Table II. The maching guns shall be tested
using the firing fixture conforming to drawing 7273925. For the
first 500 machine guns, the ammunition shall be linked together
in 100-round belts with a dummy cartridge separating each 50
rounds (see 220.127.116.11). The belts of ammunition shall hang unsup-
ported vertically from the firing fixture feed tray for a
distance of not less than 4 feet (see drawing 7273911). Subse-
quent machine guns shall be tested using M172 Dummy Inert Loaded
Cartridges every 20 rounds (see Table II).
18.104.22.168 M4 Bandoleer firing. The sample machine guns shall
be tested for functioning requirement (see 3.4.5) using the
firing fixture specified in 22.214.171.124 and using the M4 Bandoleer
attached to the machine gun. Firing shall be accomplished using
both the assigned and spare barrel assembly with biped assembly.
The M4 Bandoleer shall be loaded with a carton having a 100-round
belt of ammunition having a M172 Dummy Indent Loaded Cartridge
separating each 50 round (see 126.96.36.199) l The first 50 rounds
shall be fired in interrupted bursts (see note 1 of Table II) and
the next 50 rounds shall be fired in one continuous burst.