USNBD, British Bombs and Fuzes, Pyrotechnics, Detonators; Section II

U.S.N.B.D. - BRITISH BOMBS AND FUZES; PYROTECHNICS; DETONATORS

BRITISH FUZES & PISTOLS


		BRITISH TAIL PISTOL
BOMBS USED IN	G.P. 250 & 500 lb. Mks I,	NO. 37
	II, and IV; 1000, 1200,
	and 4000 lbs.
	M.C. Bombs
	S.A.P. 250 & 500 lb. Mk V.	*Mks IV, IV & V**
	A.P. 2000 lb. Mks I, II, III
	(actually the dimensions	(Service)
	of this pistol are idenitcal
	to the No. 28 & No. 30
	pistol, so theorstically
	sould be used in any
	bombs they might be used
	in).
FUNCTIONING	Chemical Long delay, 6 to 144 hrs. (affected by temperature)
ARMED CONDITION	Assumed armed if dropped; armed is arming fork is threaded
	down to bottom of arming fork cavity in pistol. Mks IV* & V
	have white blot paper ring in arming fork cavity to indicate
	broken ampoule.
FUZES USED WITH	None (formerly used with No. 845 anti-disturbance nose fuze,
	which is now obsolete).
ARMING TIME	8 arming fork revolutions, or instantaneous if dropped from
	sufficient height to break ampoule.
IDENTIFICATION	Similar to No. 28 & No. 30 tail pistols, except for a V-shaped
	notch around pistol in center of knurled exterior. Knurling is
	in form of cuts along longitudinal axis of pistol, instead of
	cross-cuts as in the Nos. 28 & 30. Arming vanes colored red.
MAX. BODY DIAMETER	2"
OVERALL LENGTH	4.25"

DESCRIPTION:

This pistol is a chemcial long delay type, the delays being obtained by the solvent action of acetone on celluloid; the alternative delays are provided by varying the num-ber of discs used. The pistol is constructed in three main parts: the head, the body, and the anti-removal device. The head and body are screwed together and locked by a locking screw. A rubber insertion washer and a soft rubber washer are located between the head and the body when the two components are assembled. Into the head of the pistol is fitted an arming screw, on the spindle of which is assembled a soft rubber washer and a steel washer, which seal the acetone in the fuze when the arming screw is threaded inwards sufficiently to break the ampoule. The glass ampoule containing acetone fits into the body of the pistol, resting on a perforated zinc disc over the wedge-shaped seating. This seating is threaded down into the body. The striker spring is held in compression by the head of the striker screw which is engaged in a counter-sunk celluloid disc inserted at the top of the assembly. The striker sleeve is retained by 16 retaining balls seating on the retaining sleeve. The compressed striker sleeve spring is located between a shoulder in the bore of the pistol body and a shoulder on the stri-ker sleeve. The anti-withdrawal device consists of a soft rubber washer assembled over a retaining sleeve which is screwed on to the bottom of the pistol body, and which is reduced in diameter at the bottom to fit into the head of the detonator when in the bomb. The retaining sleeve is locked in position in the detonator head by the soft rub-ber washer. A step is porvided on the retaining sleeve which is positioned against a corresponding step on a lock ring when in the bomb. The lock ring is secured to the pistol body by a locking screw. The pistol is fitted with a tab locking device and is pro-vided with a safety plate which has slots to allow it to fit down over the fork of the arming screw and onto two recesses in the pistol head.

OPERATION:

On release of the bomb, the arming screw of the pistol is screwed down by rotation of the arming vanes of the bomb tail and crushed the ampoule, thus releasing the ace-tone. In descending, the head of the arming screw compresses the soft rubber washer, which seals the acetone in the pistol. The solvent action of the acetone on the celluloid disc or discs continues until the countersunk head of the striker is released from the countersunk celluloid disc, thus allowing the striker to be moved forward by the action of the striker spring.

The retaining sleeve is locked in the detonator head by the soft rubber washer, and any attempt to remove the pistol from the bomb by unscrewing the body will result in the body's unscrewing from the retaining sleeve. After unscrewing the body approxima-tely one-half turn, the retaining balls are released, allowing the striker assembly to move forward by action of the struker spring and force the striker against the cap in the detonator.

EARLY MARKS COMPARED:

Mks I & II are obsolete; Mk I did not have anti-withdrawal device. Mk III incorporat-ed anti-withdrawal device, arming screw had left-hand threads. Mk IV has right hand thread arming screw. Mks IV* and V are similar to Mk IV, but have a white blotting pa-per ring to indicate a broken ampoule.

REMARKS:

(1) This pistol has a needle striker, and all marks use No. 39 or other sensitive type detonator.

(2) 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.

(3) DO NOT WITHDRAW THIS PISTOL FROM A BOMB.

(4) Bombs in which used usually have arming vanes and fins painted red.

(5) Latest model of the No. 37 pistol have eliminated the anti-withdrawal device, substituting instead a striker guide. The V-shaped groove is painted white, making it indistinguishable from No. 53 and 53A pistols. No. 37 pistols will still be found, however, with unpainted groove and anti-withdrawal device.