Tail Pistol No. 37 Mks IV, IV*, IV**, V, V*, and VI (Service)

Description: This is a chemical long-delay pistol with a sensitive-type striker. Delays are obtained by the action of acetone on celluloid. Alternative delays result when the number of celluloid discs is varied. The pistol is constructed in three main parts, the head, body, and antiremoval device. The head and body a screwed together and locked by a locking screw. A rubber insertion washer and a soft rubber washer are located bet-ween the head and the body when assembled. Into the head of the pistol is fitted an arming screw, on the spindle of which is placed a soft rubber washer and a steel washer. The seals the acetone in the fuze when the arming screw threads inward and breaks the ampoule.

The glass ampoule containing acetone fits into the pistol body and rests on a perfo-rated zinc disc over the wedge-shaped seating. This seating is threaded into the body. The striker spring is held compressed by the head of the striker screw, which is engaged in a countersunk celluloid disc inserted at the top of the striker assembly. The striker sleeve is retained by 16 retaining balls which seat on the retaining sleeve. The compres-sed striker-sleeve spring is loacted between a shoulder in the bore of the pistol body and a shoulder on the striker sleeve.

The anti-withdrawal device is a soft rubber washer assembled over a retaining sleeve, which is screwed onto the bottom of the pistol body. This sleeve is smaller at the bottom to fit into the head of the detonator when in the bomb. The soft rubber washer locks the retaining sleeve into position in the detonator head. A step on the retaining sleeve is po-sitioned against a corresponding step on a lock ring when in the bomb. A lock screw se-cures the lock ring to the pistol body. The pistol has a tab locking device.

The Pistol No. 37 is similar to Tail Pistol No. 28 and No. 30 externally, except for a V-shaped notch around pistol in center of knurled exterior. Knurling is in form of cuts along the longitudinal axis of the pistol, instead of crosscuts as in the Nos. 28 and 30.

Operation: On release of the bomb, the arming screw is screwed down by the arming vanes of the bomb tail and crushes the ampoule, thus releasing the acetone. In descen-ding, the head of the arming screw compresses the soft rubber washer, sealing the ace-tone into the pistol. The acetone attacks the celluloid disc or discs until the countersunk screwhead of the striker is released, thus allowing the striker to be moved forward by the action of the striker spring.

The soft rubber washer locks the retaining sleeve into the detonator head. Any at-tempt to unscrew the pistol body from the bomb will result in the body's unscrewing from the retaining sleeve. After approximately one-half turn, the retaining balls are released and the  striker assembly moves forward by action of the striker spring to force the stri-ker against the cap in the detonator.

Remarks: Mks I and II of the Pistol No. 37 are obosolete. Mk I had no anti-withdrawal devcie. Mk III incorporated an anit-withdrawal device, but the arming screw had left-hand threads. Mk IV has a right-hand-thread arming screw. Mks IV* and V are similar to Mk IV, but have a white blotting-paper ring to indicate a broken ampoule. These fuzes employ arming vanes which are painted red.

Mks IV**, V* and VI of the Pistol No. 37 have no anti-withdrawal device. The V-sha-ped groove is painted white. The Mks IV** and V* are converted Pistols Mk IV* and Mk V. Mk VI is manufactured to a modified design. The arming vanes employed with these pistols are painted white.

Delays intended for this pistol are indicated by a letter after the number: No. 37, 6 hours; No. 37A, 12 hours; No. 37B, 36 hours; No. 37D, 72 hours; No. 37E, 144 hours.

Figure 133 - Tail Pistol No. 37 Mk V