PISTOLS CAUSES OF FAILURE AT 500 FOOT SETTING

2. The most common causes of failure of Mark 6 Mod. 1 pistols to operate satisfactorily when subjected to standard functional test at 500 ft. setting (Chapter V, Paragraph 8) are:

(a) Leakage past the dial plate gasket. This may be due to failure to securely the dial plate locking ring. After screwing this ring into place with the dial plate lock ring wrench the ring should be set up by use of a drift.

(b) Leakage past the ball valve in deep firing mechanism. The edge of the hole in the valve seat, against which the ball is pressed by the valve spring, is very slightly beveled. Imperfections in this beveled edgy may cause leakage.

(c) Leakage through seal between neck of depth setting sleeve and dial plate. This may be caused by failure to screw deep setting mechanism tightly into place. Improperly fitt-ing gasket or one not correctly assembled would also permit leakage at this point.

(d) Leakage past the gland around valve seat in deep firing mechanism. This may be caused by failure to tighten the gland nut securely.

(e) Chips of metal or dirt in valve seat.