MARK 6 MOD. 1 PISTOL DEEP-FIRING TEST

8. The standard deep firing functional test procedure for completely assembled pistols using hydrostatic pressure in pistol testing fixture is described below. This test is not ad-visable for testing more than one percent of a lot. See note in paragraph 8 (m). The pro-cedure of chapter VI paragraph 16 should be followed to test the deep firing feature of each Mark 6 Model 1 pistol tested.

(a) Remove the detonator and safety cover if 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 on deep firing mechanism at "500".

(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 plate.

(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 tighten the screw securely.

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

(i) Open valve C to allow hydrostatic pressure to build up in fixture to about 10 psi on 0-300 lb. gauge. Open valve N to purge entrapped air in test fixture. Close valve N.

(j) By use of valve C admit pressure to test fixture. Control the valve so that the gauge pressure rises at the rate of approximately 6.5 pound per second.

(k) Watch the gauge closely during the pressure rise. A slight flicker of the gauge needle denotes the operning of the valve in the deep firing mechanism. Firing of the pistol takes place immediately thereafter. Note the pressure when the valve opens. A pressure of 222 psi is equivalent to 500 foot depth of sea water and a pressure of not less than 197 psi and not more than 247 psi when the valve opens indicates a satisfactory pistol. Close valve C immediatley after the pistol fires.

(l) Open valve N to drain the fixture. Back off head holding down screw by turning hand-le. Unlatch carrier and swing it to one side. Remove pistol from the fixture.

(m) Pistols subjected to this test must be disassembled, blown out with air and then pla-ced in an oven at 220° F for at least 4 hours to remove all traces of moisture from the mechanism.

Reassembled pistols with damaged parts replaced may be issued to service after calibra-tion and test as noted in Chapter VI.

NOTE: Because of the reconditioning necessary after this test it is not available to test more than one per cent of a lot. In the early stages of manufacture attempts were made to use air for this test so that it would not be necessary to break down the pistol for drying. However, it was found that the deep firing mechanism valve would not function properly under air pressure.