LOADING DEPTH CHARGES INTO RELEASE TRACKS OR PROJECTORS

12. For instructions in loading depth charges into release tracks or projectors see O.P. No. 35 "Depth Charge Release Track, Mk. 1"; O.P. No. 721 "Depth Charge Release Tracks, Mk. 3"; O.P. No. 63, "Depth Charge Projector, Mk. 1"; or O.P. No. 831, "Depth Charge Projector, Mk. 6 Mod. 1"; O.P. No. 904, "Depth Charge Release Gear", under preparation, will cover all types of depth charge tracks. It will supersede O.P.'s Nos. 35 and 721 when it is issued.

REMOVING AND CHANGING SAFETY FORKS AND PISTOL COVERS

13. Plain (shipping) safety forks on booster-extenders and plain safety covers on pistols must be removed and replaced with knobbed safety devices after depth charges are loa-ded into release tracks.

14. A plain safety fork may be easily removed from a booster-extender by engaging the hook on the extender testing tool in the hole in the fork and pulling the fork clear of the spindle of the mechanism. After the fork is removed, the spindle will spring inward about ¼-inch. The hook on the testing tool may be used to pull the spindle outward far enough to permit installation of the knobbed safety fork.

15. The plain cover on a pistol may be removed by unscrewing it from the inlet valve or the deep firing mechanism of the pistol. A knobbed cover is installed on the pistol by me-rely screwing it on firmly, in place of the plain cover. The safety is installed to keep the interior of the pistol mechanism dry. For this reason it should be firmly secured in place. However, a pipe wrench, pliers or other tool should not be applied to the knob for the purpose of screwing on the safety cover. A good grip with the thumb and forefinger app-lied at the rim of the cover will be sufficient to form a tight seal.

15. A. - Attached Sheets (Change 2)

16. When a depth charge is placed on a projector, the plain shipping fork and plain safe-ty cover are to be left in place until immediately before the projector is fired. (It is inten-ded that paragraph 19. of O.P. 831, July 1942, shall be revised in this respect.) The plain safety fork and plain safety covers remain in place while depth charges are in roller loa-ders.

SETTING DEPTH ON PISTOL

17. Pistols should be set for the desired firing depths at a time prescribed by the Com-manding Officer.

SETTING THE MARK 6 PISTOL

18. Set a Mk 6 pistol as follows:

(a) Place the depth-setting wrench on the index pointer of the pistol, with the open sec-tion of the wrench fitted over the arrow on the pointer. Turn the pointer in a counter-lockwise direction from SAFE to 30, or in a clockwise from 30 to SAFE.

(b) When setting the pointer in a counterclockwise direction to 30, do not attempt to force it past the 30 mark and against the stop pin. Likewise, when moving the pointer clockwise to SAFE, do not attempt to force the pointer past the SAFE mark and against the stop pin. The attachment of safety stop for the depth setting wrench is intended to prevent moving the index pointer beyond its limits. If this is done it may result in shearing off the index pointer stop pin. As a consequence, the proper relationship between the adjusting bushing and the depth-setting sleeve will be destroyed. And when the index pointer is subsequently rotated counterclockwise, the adjusting bushing will be forced against the hydrostatic piston to produce a highly unreliable depth setting or cause firing of the detonator during the setting operation.

SETTING FOR LESS THAN 300 FEET

SETTING THE MARK 6 MOD. 1

19. Set a Mk 6 Mod. 1 pistol as follows:

(a) To set the pistol for a depth of 300 feet or less, remove the safety cover and see that the deep-firing mechanism pointer is set at the 0-to-300 mark on the inner dial. If it is not, set it by turning the pointer with a screwdriver (or the screwdriver end of the depth-setting wrench). Replace the safety cover and set the outer pointer for the desi-red depth as directed in paragraph 18.

setting for greater than 300 feet

(b) If the depth charge is to be set to fire at a depth greater than 300 feet, set the in-dex pointer at the 100-foot mark on the outer scale. Remove the safety cover and turn the deep-firing mechanism pointer to the desired setting. Replace the safety cover.

NOTE: The strength of the index pointer stop pin in the Mark 6 Mod. 1 pistol has been increased. However, instructions noted in paragraph 18 (b) above must be ob-served.

The installation of a seal, between the dial plate and the neck of the depth setting slee-ve to make this pistol watertight, increases the torque required on the depth settin wrench as compared with the Mark 6 pistol. Generally thighness at this point is a goode assurance against leakage and should not cause concern as to the condition of the pis-tol. However, instances may occasionally be encountered where it is practically impossi-ble to turn the index pointer. This may be caused by binding between the piston stem and the wall of the hole in the adjusting bushing. Pistols defective in this respect should be reconditioned.