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Page Title:
Measurement of copper pressure cylinders |
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|  MIL-C-46409D (AR)
APPENDIX "D" (CONT'D)
40.0 MEASUREMENT OF COPPER PRESSURE CYLINDERS
40.1 The chamber-pressure shall be determined by using the radial copper pressure
cylinders. One cylinder shall be used for each cartridge fired.
40.1.1 The copper pressure cylinder shall be measured individually using a properly
calibrated micrometer graduated to 0.0001 inch. The cylinders shall be measured prior to firing,
measurements recorded and the cylinders placed in a recessed holding block in such a manner
that their identity is maintained throughout the test.
40.1.2 Upon completion of the firing, the cylinders shall be measured again and the
decrease in length obtained for each cylinder by subtraction of the actual readings. The
decrease in length obtained for each cylinder shall than be applied to the appropriate target table
(a target table is supplied with each box of copper pressure cylinders) and the corresponding
chamber pressure (PSI) shall be recorded on the test report form in such a manner that the
velocity of each cartridge can be identified with the corresponding chamber pressure obtained
Velocities recorded at other than ambient are for information only.
40.2 Whenever a new supply of copper pressure cylinders is received involving the use of
different target tables, they shall be tested in comparison with the cylinders being replaced by
firing forty-four (44) standard (reference) cartridges for chamber pressure in a barrel assembly of
know characteristics, using twenty-two (22) of the new cylinders in alteration with twenty-two
(22) of the old cylinders shall not vary by more than 800 PSI from the mean obtained with the
old cylinders. If this limit is exceeded, the new lot is considered unacceptable and reported to the
responsible agency.
40.3 TEST PROCEDURE
40.3.1 Pre-firing (Preparation for test)
40.3.1.1 The required number of test and standard (reference) cartridges shall be placed in a
vertical position primer end down, in recessed holding blocks.
The cartridges shall be permitted to come to a temperature of 60 and 80F prior to being placed
in the temperature-controlled room or container in such a manner that all cartridges are subjected
to a uniform temperature for a minimum of two hours, prior to firing. The container or room
shall be maintained at a temperture of 70F+2 F, with a relative humidity of 60 percent, 5
percent, and be sufficient capacity to allow free circulation of air.
40.3.1.2 The pressure-barrel assembly is assembled in the test fixture on the mount. The
chamber and bore of the barrel are wiped dry. The barrel is then boresighted into position.
40.3.1.3 The following measurements shall be made before a barrel assembly placed in
service, after misfires, pierced primer, flowbacks or whenever a part replacement has been made
in breech-block assembly.
Limits
.011" - .015"
Firing-pin-indent
.060" - .068"
Firing-pin protrusion
.058" - .060"
Headspace
31
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