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|  MIL-C-14858A (AR)
AMENDMENT 3
PAGE 15
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4.4.4, Delete in its entirety and substitute the following:
"4.4.4 Action time. The test shall be performed by either using a velocity test barrel or
EPVAT test method.
4.4.4.1 Action time measurement by velocity test barrel. The test shall be
conducted in accordance with the methods and procedures in SCATP - 7.62mm using
equipment listed in EL 8648129.
4.4.4.2 Action time measurement by EPVAT method. The test shall be conducted
simultaneously with velocity and chamber pressure using the methods and procedures in
SCATP - 7.62mm. The EPVAT test barrel, drawing no. 12983006, shall be used with the
equipment listed in EL 8648129."
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4.4.5, Delete in its entirety and substitute the following:
"4.4.5 Velocity.
4.4.5.1 Pre-conditioning and choice of test method. Prior to the velocity test, cartridges
shall be conditioned at 70F 2F for a minimum of two hours. The test shall be conducted in
accordance with TECP 700-700, Vol III, when using the velocity barrel, and in accordance
with Appendix D of SCATP-7.62mm when using the EPVAT method.
4.4.5.2 Selection and "breaking-in" of velocity barrel assemblies. Five velocity barrel
assemblies for the velocity test shall be selected from a quantity of eight chamber pressure
barrels using the long piston. Prior to the firing of 30 reference cartridges through each of the
eight candidate barrels - as described in the next sentence - each of the eight candidate barrels
shall be "broken in" by firing 100 standard ball cartridges through them. (ONCE BROKEN
IN, THE BREAKING IN PROCESS SHALL NOT BE REPEATED.) Selection of the five
velocity barrel assemblies to be used as described in 4.4.5.3 below, shall be made by firing 30
reference cartridges through each of the eight candidate barrels and making the selection of
five from among those that have the lowest standard deviation for velocity.
4.4.5.3 Testing procedures. First of all, there shall be three test cycles, one cycle on each
of three succeeding days. FIRST DAY: (1) twenty reference cartridges shall be fired in each
of the five selected-out barrel assemblies; (2) the average velocity and standard deviation of the
velocities for each velocity barrel assembly and the average velocity for the five barrel
assemblies shall be computed; (3) if the average velocity of any barrel assembly varies from
the average of the five barrel assemblies by more than 14 feet/second, then that assembly
shall be withdrawn from the test cycle and another selected using the procedures described in
4.4.5.2, above; (4) having selected a replacement barrel assembly, velocity testing for the first
day will recommence in (1), (2) and (3) until the cartridge velocity variance criterion is met.
THEREAFTER, ON TWO SUCCESSIVE DAYS, THE SAME FIVE VELOCITY
ASSEMBLIES SHALL BE USED: (1) an additional 20 cartridges shall be fired each day in
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