The shell is fired from the 149 mm 13 calibre field howitzer with a separate loading Q.F. cartridge and, without the fuze, is 25.96 inches (approx. 4.5 calibres) long. From the nose to the shoulder the shell is painted red or orange and from the shoulder to a 1.6 inch green band above the copper driving band the body is sheradised and is pale blue. Behind the driving band the shell is painted white and has two black strips painted at right angles across the base and contained up the wall to the driving band, thus produ-cing four black longitudinal strips behind the band. The weight marking "Kg. 42" and the letters "M.B.T." enclosed in a rectangle which indiacte the bursting charge to be shellite are stencilled on the ogive. The calibre in millimetres and the length of the howitzer in calibres are stencilled at about the centre of the body in form "149/13". A small alumini-um tranist plug with knurling near the head protrudes from the Inneschi fuze in the fuze hole at the nose. The weight of the shell, filled and fuzed, is approximately 93 lb. 8 oz. The weight of the bursting charge is 16 lb. 7 1/2 oz.

The shell, weighing 85.74 lb., consists of three main parts, the body, the diaphragm and the head.

The body is of forged steel with a comparatively thin wall and a correspondingly high high capacity. A narrow driving band, wholly of copper, with a single cannelure is fitted at one and a half inches from the base. There is no base plate. The forward end of the body is shaped to correspond with the contour of the ogival head and is screwthreaded inter-nally for its assembly. The cavity for the bursting charge is machined throughout and is screwthreaded at about the centre for the insertion of the diaphragm which thus strengthens the wall. The diameter of the cavity in front of the diaphragm is 4.88 inches. Behind the diaphragm the thickness of the wall is increased by the diameter being redu-ced to 4.46 inches at this part of the cavity. A chemical analysis of the steel shows the composition inclu-des:– chromium 0.69 per cent, manganese 1.26 per cent, silicon 0.24 per cent, phosphorus 0.02 per cent, sulphur 0.052 per cent and nickel 0.26 per cent. The Vickers Diamond Hardness figures average 274.

The diaphragm is a circular plate of forged steel with an external screwthread for insert-ion in the cavity. Four equally spaced holes of 0.79 inch diameter are drilled about mid-way from the centre. The underside is recessed.

The head is ogival with a fuze hole at the nose and is of forged steel machined internally and externally. The lower portion screwthreaded externally for assembly with the body.

The 16 lb. 7 1/2 oz. bursting charge of shellite 60/40 (trinitrophenol 60, dinitrophenol 40) is contained in two cartons, inserted with paraffin wax, one in each part of the cavity. The cartons are made of thick paper interleaved with aluminium foil and are fitted with aluminium end pieces. The carton in the lower part of the cavity is cylindrical and con-tains a 7 lb. 7 1/2 oz. block of shellite. A card-board disc is inserted in the base of the cavity below the carton and a felt disc is placed over the head. The recess in the under-side of the diaphragm contains a cardboard disc with perforations corresponding with those in the diaphragm. A similar disc covered by a disc of thin card-board covers the front face of the diaphragm.

The carton in the upper part of the cavity is shaped to suit the ogival head of the shell and includes a paper tube closed at the base to line the exploder cavity and contains a steel exploder container. The exploder container is screwed to the gaine and has a felt disc at the base. The carton contains a 9 lb. block of shellite and has a felt washer pla-ced over the head.

The exploder container, screwed to the gaine, contains 43.5 grams of graphited ballistite in the form of 0.022 inch cubes. The ballistite consists of nitrocellulose 50.47 per cent (Nitrogen content 12.25 per cent), nitroglycerine 48.96 per cent, and 0.57 per cent of graphite.

The fuze is of the Inneschi type described in Pamphlet No. 7 but has a larger body. The gaine consists a 5 gram filling of ballistite and differs from the 2.3 gram type shown in Pamphlet No. 7 (Fig. 8C) in being longer. The lower portion of the body is reduced in dia-meter and screwthreaded for insertion in the top of the exploder container. The ballistite consists of 57.82 per cent of nitrocellulose (Nitrogen content 12.12 per cent) and 42.18 per cent of nitroglycerine.