This round is fired by the 4.7 cm anti-tank gun mounted on the S.P. armoured chassis I B.

The shell contains a bursting charge of cast T.N.T. in which a cavity is formed which contains T.N.T., pressed to a density of 1.44. A brass container, to receive the maga-zine of the fuze, is inserted into a cavity formed in the pressed T.N.T. at the fuze hole. The weight of the filling is 6 oz. 3.9 dr. (cast T.N.T. 5 oz. 14 dr. pressed T.N.T. 5 oz. 9 dr.) and weight of the filled shell is 3 lb. 2 oz. 2 dr.

Fig. 9 German 4.7 cm H.E. Shell

The fuze used is of the direct action detonating type in which the needle is held off the detonator by four steel balls.

The hollow stemmed aluminiuim needle with enlarged head passes through a cup-shaped ferrule and is supported at the cone, near the point, by four steel balls. The balls are located in an internally coned metal cup and retained by the ferrule which is pressed on to them by the spiral spring. The cone of the needle corresponds with the coned interior of the cup so that a force acting along the axis of the needle will not displace the balls. The head of the needle is housed in a recess in the cap of the fuze, the recess closed against air pressure by a copper disc.

The magazine is screwed into the underside of the fuze and contains the initiator compo-sition in a copper capsule over a 0.48 gram filling of P.E.T.N. The copper capsule has a copper disc soldored in the front end and a second copper disc, with felt washer attach-ed, interposed between it and the needle point. The initiator filling in the capsule con-sists of a 25 gram layer of detonating composition over 0.31 grams of lead azide. The detonating composition consists of: mercury fulminate 28.7 per cent, potassium chlorate 39.8 per cent, and antimony sulphide 31.5 per cent.

The fuze is fitted with a brass cover secured by a tear-off strip. The strip is provided with a finger ring which is lightly soldered to the cover.

The cover is removed before loading. During acceleration the balls are held by set back and the ferrule. When acceleration ceases and the rate of spin is sufficient the balls are forced outward by centrifugal force and retained in this position by the ferrule under the pressure of the spring. The needle is then held off the detonator by creep action. On im-pact the needle is driven in and pierces the detonator.

The copper disc over the initiator capsule is probably intended to act as a resistance to the needle and to prevent premature action by wind pressure acting on the needle such as might occur if the copper disc in the cap of the fuze were punctured.

Neither the needle, ferrule, not the spring are positively located, and it appears that the needle head is so designed that the point of the needle may rove considerably off its normal axis without jamming, which, should it occur, would render the fuze intensitive on a light target.

Fig. 10