MIL-DTL-001298D (AR)
4.8 Firing pin release. Ten bolt assemblies taken at random from each lot of M2s
shall be tested. The firing pin release test shall be performed using approved fixture
Drawing 6511053 or 7270150. A load shall be applied slowly and uniformly at the following
points until the firing pin is released: First to the sear slide on one side; second, with the sear
slide reversed to the other side; and third, directly to the sear from the top. The load shall be
applied five times at each of the three points.
4.9 Firing pin indent. The firing pin indent, when taken in Government Standard
copper compression cylinders Drawing 8440920 inserted into a holding fixture Drawing
5520627, shall be computed by measuring the distance from the original surface before
indentation) of the cylinder to the bottom of the impression.
4.10 High pressure resistance. Each M2 shall be mounted in a firing fixture with
safety cover conforming to Drawing 8440929 or approved equivalent and tested by firing one
high pressure test cartridge. After proof firing, the high pressure cartridge case shall be
visually examined for bulges, splits, rings, and other defects caused by defective barrels.
4.10.1 Magnetic particle inspection. The M2 shall be examined for cracks,
deformations, or other damage; and the bolt subassembly, barrel extension assembly, barrel
assembly, and receiver assembly shall be magnetic particle inspected in accordance with
ASTM E 1444 and drawings 6147463, 5504082, 7265156, and 6535480.
4.11 Functioning. Each M2 shall fire 50 rounds right side feed and 50 rounds left side
feed using a test fixture Drawing 8440929. Each 50 round segment shall be fired 25 rounds
spasmodic and 25 rounds continuous burst. Parts within the receiver group, cover group, and
bolt group shall be disassembled from right side feed and reassembled for left side feed. M2s
that fail to fire 50 rounds right or left hand feed test may be retested and accepted if the above
procedure is successfully repeated.
4.11.1 Functioning alternate sample size. If 500 consecutive M2s meet the
requirement, the number of M2s to be tested each month of production shall be reduced to two
M2s or 5% of the total monthly production rounded up to the next higher whole number,
whichever is greater (see 6.11).
4.12 Belt pull. Each M2 shall be tested for belt pull using the applicable pieces of the
belt pull test fixture Drawing 8440929. Fire a 10 round burst right side feed and a ten round
burst left side feed. The ten round metallic linked belts shall be loaded with ten rounds of live
and two rounds of dummy ammunition. The live ammunition shall feed into the machine gun
first. The turn-buckle part 15 of the fixture shall be adjusted to feed the rounds horizontally or
with not over a 5 degree rise from the pulley to the feedway of the weapon. M2s that fail to
fire the initial ten round burst right or left hand feed may be retested and accepted if the above
procedure is successfully repeated. M2s may be mechanically gymnasticated for a period not
longer than ten minutes prior to retesting.
4.12.1 Belt pull alternate sample size. If 500 consecutive M2s meet the requirement
the number of M2s to be tested each month of production shall be reduced to two M2s or 5%
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