The shell fitted with a 10.9 inch brass cartridge case carrying a Model 35 percussion pri-mer and a double base propellant charge, forms a fixed Q.F. round for the 75 mm 27 cali-bre C.K. and A.V. anti-aircraft guns. The shell is fuzed with a time fuze and, excepting a rust-proofed band near the shoulder, has either a pale blue or blue body with a 0.6 inch darker blue band painted 0.8 of an inch above the driving band. Blue shell of this type without a band marking have also been met with. The fuze-hole adapter, forming the head of the shell, has a marked reduction in diameter forming a cylindrical neck immedia-telly below the fuze. The head of the shell (i.e. the adapter and the forward end of the body) is painted an orange red. The following details are stencilled on the body in black:– "Kg. 6.3. TRITOLO" (enclosed the rectangle), "75/27 C.K., 75/27 A.V.". The time fuze is marked with a red "T" on the cap and may be fitted with a brass cover secured by a tear-off strip with finger ring. The cover also bears the red "T" and an arrow with the markings "TIRARE". The length of the complete round is 20.5 inches.

The fuzed shell is 11.2 inches in length and when filled and fuzed weighs approximately 14 lb.

The cylindrical shell body is of forged steel with a comparatively thin wall and is fitted with a copper driving band. The forward end is screwthreaded internally to receive the adapter. The body contains a fragmentation cylinder machined from grey cast iron which is grooved along its length and circumferentially on the exterior to assist fragmentation. A channel is formed through the centre of the cylinder to accommodate the bursting charge. Red lead is inserted between the exterior of the cylinder and the wall of the shell and in the fragmentation grooves. The fuze-hole adapter is machined from grey cast iron and is screwthreaded internally to two diameter to receive the gaine and fuze respecti-vely. The exposed portion of the adapter forms the head of the shell and is shaped to form a sloping shoulder with a cylindrical neck. The base of the adapter is recessed to fit over the forward end of the bursting charge.

Body

Fragmentation cylinder

Adapter

1.87 lb.

Total

12.7 lb.

The bursting charge consists of approximately 4 oz. 2 dr. of cast T.N.T. in a cardboard carton. A cavity formed in the head of the charge to accommodate the exploder is lined with a cardboard tube. A felt washer is inserted between the top of the filling and the base of the adapter and gaine and a felt disc is inserted in the bottom of the exploder cavity.

The exploder consists of 5.5 drams of ballistite flake in a cylindrical brass body. The body is approximately 3.1 inches in length with a small central hole at each end, closed on the inside by a fabric disc.

The 2.3 gram ballistite gaine used below the time fuze is described in Pamphlet No. 7.

The combustion type of time fuze, graduated to 59, described in this pamphlet.

The propellant charge is contained in a bag with a red igniter bag of gunpowder approxi-mating to G.20 tied at the base. Charges of two types are used, both being of double base propellant. One consists of 1 lb. 3 oz. 5 dr. of a ballistite in strip form, the dimen-sion of the strips being 8.3 x 0.4 x 0.038 inches. The composition of the propellant, as found by analysis is:– nitrocellulose (including inorganic matter) 60.29 per cent, nitrogly-cerine 25.54 per cent and dinitrotoluene 14.17 per cent. The bag containing the charge is marked "Ballistite Attentuata In Piastrine 1 x 10 x 210". The igniter bag contains about 160 grains of gunpowder and is marked "10 Gr.". The other type of charge consists 1 lb. 3 oz. 11 3/4 dr. of a cordite in tubular form, the external and internal diameters of the 8.05 inch tu-bes being 0.131 and 0.042 inches respectively. The composition of the pro-pellant, as found by analysis is:– nitrocellulose (including inorganic matter) 71.53 per cent, nitroglycerine 23.73 per cent and mineral jelly 4.74 per cent. The bag con-taining the charge is marked "P.O.508,008 DNC 1933" (these markings are very indistinct). The igniter bag contains about 160 grains of gunpowder.

As the result of trials it has been found that the break up of the fragmentation cylinder generally follows the lines of weakness as designed by the grooving but the segments also undergo considerable fragmentation. The dispersion of the fragments is mainly late-ral.