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MIL-C-7O725A (AR)
3.4.1.4.2 Waterproof (firing test). After immersion in
20C (68F) water for 24 hours the mean velocity of the test
cartridges shall not vary from the mean velocity obtained in the
20C dry test by more than 30 mps (98 fps).
3.4.2 Chamber pressure.  The mean chamber pressure of
cartridges, using a Government approved piezoelectric transducer,
conditioned at 20C (68F) shall not exceed 220 mpa (32,000
PSIG).  The chamber pressure of any individual cartridge shall
not exceed 255 mpa (37,000 PSIG).
3.4.2.1 Chamber pressure at extreme temperatures.  The mean
chamber pressure of cartridges conditioned at 50C (122F) and
-20C (-4F) shall not increase more than 20 mpa (2,900 PSI)
above the mean chamber pressure obtained at 20C.  The chamber
pressure of any individual cartridge, conditioned at -55, 20,50
and 68C (-65, -4, 122 and 165F), shall not exceed 255 mpa
(37,000 PSIG).  Decreased chamber pressure is acceptable.
The mean velocity of cartridges
3.4.3 Velocity.
conditioned at 20C (68F) measured at 4.57 m (15 ft) from the
muzzle of the weapon shall not vary more than 6 percent from
the design velocity.  The design velocity is the mean velocity
(uncorrected) obtained during qualification testing at 20C.
Design velocities shall be established for both 1 in 7 inch and
1 in 12 inch twist barrels.
3.4.3.1 Velocity at extreme temperatures.  The mean
velocity of cartridges conditioned at 50C (122F) and -20C
(-4F) shall not vary by more than +10 percent from the mean
velocity at 20C (for both 1 in 7 inch and 1 in 12 inch twist
barrels).
3.4.4 Action time.  The action time (overall primer
ignition, propellant burning, plus the time taken for the bullet
to exit the barrel) of cartridges conditioned at 20C (68F), 50C
(122F) and -20C (-4F) shall not exceed 2.5 ms.
3.4.5 Dispersion. For both 1 in 7 inch and 1 in 12 inch
twist barrels, the average of the mean radii of all 10-round
targets fired at a distance of 25 meters (m) from the muzzle
shall not exceed 30 mm.
3.4.5.1 Match.  The center of impact of the cartridges
fired at targets located 25 m from the weapon shall not deviate
in a vertical direction by more than 20 mm when compared to M193
Ball (when fired in a 1 in 12 inch twist barrel) and the M855
Ball (when fired in a 1 in 7 inch twist barrel) .
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