MIL-DTL-60318C (AR)
requirements. Calibration charges shall be fired alternatively with the test samples and
the muzzle velocity and pressure of all charges shall be corrected to standard conditions.
.
4.5.2 Charge weight establishment for Single-perforated (SP) propellant
4.5.2.1 Charge weight establishment for Zone 1 and Zone 2 (see Table IV). Two
groups of rounds loaded with selected weights of propellant for zones 1, 2 shall be
conditioned to 70°F plus or minus 2°F for at least 24 hours and shall be fired within five
minutes after removal from the conditioning chamber. The first group consists of seven
(7) Zone 1 charges, and the second group consists of seven (7) Zone 2 charges. From the
data obtained, a correlation between velocity and charge weight shall be derived using
linear regression (excluding any valid outlier), and the charge weight shall be calculated
which will yield the service velocity as specified in Table I for each zones 1 and 2. This
calculated charge weight shall then be loaded into rounds for zones 1 and 2 uniformity
series in 4.5.2.2. Calibration rounds shall be used to correct velocity. Alternatively,
closed bomb firings may be substituted for ballistic firings at zones 1 and 2 for charge
weight establishment only in accordance with MIL-STD-286, Method 801.1.2.
TABLE IV. CHARGE WEIGHT ESTABLISHMENT FOR
ZONES 1 AND 2
No. of
Type of
Zone
Charge Weight
Rounds
Round
7
Calibration
2
Service
7
Test
2
Estimated SP Propellant
7
Test
1
Estimated SP Propellant
7
Calibration
1
Service
4.5.2.2 Uniformity series for Zone 1 and Zone 2 (Table V). The propellant shall
be conditioned to 70°F plus or minus 2°F for at least 24 hours and shall be fired within
five minutes after removal from the conditioning chamber. Firing results at 70°F shall be
corrected to standard weapon/firing conditions (calibration round conditions). A seven
round uniformity series shall be fired at each zone as specified in Table V. The difference
between the corrected velocity obtained during the uniformity series and the service
velocity shall be compensated for by a final adjustment in charge weight using the slope
of the velocity versus charge weights curve established above. Combining the data
obtained from both charge weight establishment and uniformity series (70°F), a
correlation between velocity and charge weight shall be derived using linear regression
(excluding any valid outlier), and the charge weight shall be calculated which will yield
the service velocity as specified in Table I for each zones 1 and 2. The resultants shall be
the recommended charge weights for zones 1 and 2.
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