184.108.40.206.2 Concurrent repair parts. Concurrent repair parts
shall be tested for interchangeability requirement (see
220.127.116.11.1.2 or 3.4.7) by disassembling two machine guns,
previously tested in 18.104.22.168.1.1, as necessary, and then
reassembling them using the concurrent repair parts. No hand
refinement of parts will be allowed, and the machine guns shall
operate and function properly. This test may be performed inde-
pendently of machine gun interchangeability test specified in
22.214.171.124.1.1 and at more frequent intervals using accepted machine
guns taken from current production.
126.96.36.199 Interplant. Machine guns to be subjected to the
interplant interchangeability test shall be given preliminary
hand functioning to assure proper operating before parts are
disassembled from the machine gun. Machine guns shall be
interchanged in a manner similar to the detail plan in 188.8.131.52.1
except that parts shall be divided into six groups and, that when
disassembling, every other machine gun shall be one produced by a
different manufacturer. The machine guns shall be tested for and
comply with the requirements for headspace, firing pin indent,
trigger pull, functioning, and targeting and accuracy before and
after interchange of parts using the test methods specified in
4.5.1, 4.5.2, 4.5.3, 4.5.5, and 4.5.6, respectively. Parts shall
be identified with their manufacturer throughout the test.
Before machine guns are returned to the contractors, the original
parts shall be reassembled to their respective machine guns and
given a hand functioning test to assure proper operation.
4.5.8 Endurance test.
184.108.40.206 Firing fixture. Testing of machine guns for
endurance requirements (see 3.4.8) shall be accomplished with the
machine guns held in a firing fixture conforming to drawing
220.127.116.11 Test duration. A total of 10,000 rounds or until
failure occurs, whichever is smaller, shall be fired in the
initial test machine gun from each test lot.
18.104.22.168 Firing procedure. Firing shall be accomplished
using 100-round belts. Every other belt shall be fired in
interrupted bursts with at least 10 intentional interruptions in
firing. All other belts shall be fired in one continuous burst.
The assigned barrel assembly with biped assembly shall be
interchanged with the spare barrel assembly with biped assembly
every 299 rounds throughout the entire test. For the first half
of the endurance test, the belts of ammunition shall half
unsupported vertically from the firing fixture feed tray for a
distance of not less than 4 feet (see drawing 7273911); and the