 |
|||
|
|
|||
| ||||||||||
|
|  MIL-C-14858A (AR)
AMENDMENT 3
APPENDIX A
A.5.7 The linearity determination for the transducers shall be performed as stated in
Annex 1 after each time an accumulation of 500 cartridges has been fired on the transducer.
A.6 PREPARATION
A.6.1 The required number of test and reference cartridges shall be placed in a vertical
position, primer end down, in recessed holding blocks. The recessed holding blocks containing
the cartridges shall be placed in a temperature-controlled container or room 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 temperature of 700F + 20F, with a relative
humidity of 60 percent + 5 percent, and be of sufficient capacity to allow free circulation of air.
A.6.2 The test barrel is assembled in the test fixture on the mount. The chamber and
bore of the barrel are wiped dry. The barrel is then bore sighted into position.
A.6.3 The test fixture assembly shall be in conformance with the latest IEL.
A.6.4 The transducer mounting hole shall contain NO particles of foreign material.
A.6.5 The transducer shall be installed within the test barrel as per the instructions
detailed in Annex 2. The firing mechanism shall be fitted with a device that reliably transmits an
electrical signal to initiate timing on a chronograph at the instant of contact between firing pin
and primer. The chronograph stop pulse shall be provided by antenna bar and channeled to a
signal conditioning unit through the filtered amplifier. The signal conditioning unit shall not
"load down" nor adversely affect the characteristics. A suitable chronograph shall be used such
that the action time measurement error shall not exceed + 2 microseconds.
A.6.6 The velocity screens are checked for position. It is of the utmost importance that
the screens be placed in their proper positions; measurements must be within 1/8 inch. Velocity
screens shall be checked for position. The instrumental point (mid-point between screens) shall
be 78 feet from the muzzle of the barrel. The baseline is 100 feet between screens.
A.7 CONDUCTING THE TEST
A.7.1 Five warning (fouling) shots shall be fired. Velocity, pressure and action time
readings shall be recorded to assure that the measuring equipment is functioning properly. After
the last warming shot, the chamber pressure transducer shall be re-tightened to the appropriate
torque level specified in Annex 2.
A.7.2 When firing EPVAT at 700F, the recessed holding blocks containing the reference
and test cartridges shall be removed from the controlled temperature room or box and placed at a
point convenient to the technician, provided the temperature of the firing room is approximately
700F + 20F. If the firing room is not at approximately 700F + 20F, the cartridges shall be placed
7 (23)
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals