The shell of this muzzle loading round is fitted with a propellant container at its base which carries a copper driving band. Before firing the driving band is flush with the wall of the container and does not obstruct loading from the muzzle. On firing the copper hand is expanded by the propellant gases to engage the rifling. The propellant container also carries the means of ignition in the form of a percussion primer.

The round is fitted with a brass direct action fuze, marked with Japanese characters, and is painted black with a red tip, a yellow ring below the shoulder if the shell and a white band immediately above the junction of the shell and the pro-pellant container. A round of this typ has been found with the figures 3349 stamped in the driving band and inside the base plug. The length of the complete round is 5.75 inches, the diameter 2 in-ches and the filled weight 1 lb. 8 oz.

The shell body is of steel with a rounded head and a comparatively thin wall. The fuze hole at the nose has a left-hand thread. The shoulder is of higher diameter than the re-mainder of the round and apparently acts as a guide band in the bore. The base of the shell is closed by a steel screwed base plug which has a concave inner face and also provides the means of attachment for the propellant container. The bursting charge, consisting of a approximately 5 oz. of T.N.T., is provided with a cavity to receive the magazine of the fuze. The cavity is lined with a flanged aluminium container.

The steel cup-shaped propellant container is screwthreaded internally at the mouth for assembly on the protruding base plug of the shell and is reduced in its external diameter for the greater part of its length to receive the flat copper hoop forming the driving band. A number of radial channels, lightly closed by tin-foil, are formed in the wall of the container near the base end of the portion carrying the driving band. These admit gas pressure for the expansion of the driving band. The base of the container has eight per-forations for the escape of pressure arranged in ring and central perforation for the stri-ker leading to recess in the inner face with contains the primer. The perforations are lightly closed by a paper disc adhering to the base of the container. A copper container with a cover is carried inside the container to receive the ring shaped shellacked paper bar holding the propellant.

The propellant charge consists of approximately 46 grains of finely graphited nitrocellu-lose flake. The approximate dimensions of the rectangular flakes are 0.028 x 0.024 inch. The thickness varies from 0.003 inch downwards. The nitrocellulose, which forms 95.7 per cent of the propellant, has a nitrogen content of 13 per cent.

The cylindrical brass body of the primer has a cap chamber with anvil and two fire chan-nels formed in its base and a magazine containing gunpowder. The forward end of the body is castellatel. Details of the filling of the percussion cap are not available.

The brass fuze is of the direct action type and is marked in Japanese characters.

The body is screwthreaded with a left-hand thread for insertion in the shell and has a magazine screwed in at the underside. The magazine is fitted with a detonator secured by a screwed plug at its upper end. Details of the filling of the magazine and detonator are not available.

The brass head of the fuze which is screwed into the body has a hole at the nose for the protuding head of the striker and is recessed internally for the striker assembly and the ferrule.

The striker assembly consists of a steel striker with a brass cup-shaped head and sleeve attached at its outer end. The head is changed to engage the step formed in the head of thr fuze. The sleeve which extends over the greater part of the striker has two sluts extending from the open end to the striker head and contains the striker spring arming spring. The brass support washer for the ferrule separates the two springs and the two arms formed on the washer protruding through the slots in the sleeve form a support for the ferrule. Before the loading of the round the ferrule the further supported by a two-pronged safety pin inserted through the body. Four brass segments are positioned bet-ween the inner end of the striker sleeve and the diaphragm of the body. These segments are retained in this position by the cylindrical arming sleeve.

The ferrule is in the form of an inverted cup. A hole in the base of the cup fits round the striker sleeve and an internal groove near the mouth engages the arming sleeve when the fuze is armed.

The safety pin is removed before loading. On acceleration the ferrule sets back over the arming sleeve taking with it the support washer and compressing the arming spring. The projecting arms on the arming sleeve engage in the groove in the ferrule and thus lock these two components together. During flight the arming sleeve spring, acting on the support washer, moves the ferrule forward and, taking with it the arming sleeve, leaves the segments free to be thrown clear by centrifugal force. The striker is then held off the detonator by the spring only. On impact the striker is driven in and pierces the deto-nator.