TESTS OF MARK 6 AND MARK 6 MOD. 1 PISTOLS

(Pistol Testing Fixture) Test Set Mark 3

7. The standard functional test procedure for these pistols using pistol testing fixture of the Test Set Mark 3, is a follows:

(a) Remove the detonator and safety cover is attached.

DO NOT replace the detonator collar and detonator holder.

(b) Cock the pistol. Use the cocking tool provided in the Mark 2 Mod. 1 test set for this purpose. In the cocking operation push inward on the cocking tool until its shoulder con-tacts the detonator holder. Repeat the operation several times to insure that the firing plunger lock balls are firmly seated on the beveled edge of the guide tube bushing. Alt-hough the premature firing of an improperly cocked pistol in the test set, without atta-ched detonator, will not have harmful results, accidental firing of detonator from this cause has resulted in serious injury to personnel. THEREFORE THE COCKING OPERATION SHOULD ALWAYS BE PERFORMED WITH CARE.

(c) Turn the index pointer back and forth several times through the full range from "safe" to "30". See Chapter IV paragraph 19 (b).

(d) Set the index pointer at "100". Set the pointer in deep firing mechanism of Mark 6 Mod. 1 pistol at "0-300".

(e) Draw up fixture head by turning handle of holding down screw. Unhook carrier latch and swing carrier to one side.

(f) Place pistol in fixture and swing carrier back into place with latch secured under fix-ture top pate.

PISTOL TESTING FIXTURE

(g) Clamp head in place on flange of pistol by turning handle of holding down screw. A piece of tubing may be used on this handle to tigthen the screw securely.

(h) Close valves D, E, F, G, and N and open valves H and K in testing fixture piping sys-tem.

(i) Apply air to test fixture by operating valve C and note pressure at firing on 60 lb. gauge adjacent to fixtrue. Close valves C and K when the gauge shows a pressure of 30 psi. Watch the pressure gauge. If the pressure loss in he system is not more than five pounds in one minute, the pistol is sufficiently tight.

(j) If the gauge shows falling pressure check for leaks. Be sure that the holding down screw is pulled down tightly to press the head gasket on pistol flange and inlet and out-let connections.

(l) if the leak persists, tag the pistol to indicate the fault and set is aside for recondition-ing at an overhaul station.

(m) If the pistol proves to be sufficiently air-tight, determine its firing depth as follows:

(1) Open valve "C" slowly until pistol fires. Although detonator collar and detonator holder have been removed from the pistol and the firing plunger strikes against the rubber buffer in the test fixture pistol cocking pin, and audible click when the pistol fires will be heard.

(2) Note the pressure when the pistol fires. A pressure of 44.4 psi is equivalent to 100 foot depth if sea water, and a pressure of not less than 40 psi and not more than 49 psi when the pistol fires indicates a satisfactory pistol. To get the exact reading at the instant the pistol fires, watch the gauge closely. Close valve "C" im-mediately after the pistol fires.

(3) Also check pressure required to fire at 30 foot setting. Firing should occur bet-ween 10 and 15 psi.

(n) Open valve "N" to relieve the pressure in fixture. Raise up on pistol cocking lever to recock the Mark 6 pistol. Repeat this operation several times to insure proper seating of firing plunger lock balls on beleved edge of pistol central tube bushing.

NOTE: This recocking operation cannot be performed on the Mark 6 Mod. 1 pistol because the ball valve in the deep firing mechanism is forced against its seat by the air retained in the pistol hydrostatic chamber.

To recock the Mark 6 Mod. 1 pistol after test, release entrapped air in pistol hydros-tatic chamber by pressing down on ball valve with a tool provided for this purpose.

(o) Back off head holding down screw by tunring handle. Unlatch carrier and swing it to one side. Remove pistol from the fixture.

(p) Replace detonator collar, detonator holder and locking spring. Recock the Mark 6 Mod. 1 pistol as noted in paragraph 7 (n) above.