148. The 60-mm Illuminating Shell M83, designated as above, is used by ground troops to illuminate objectives beyond the range other pyrotechnic ammunition. It is fired from a 60-mm mortar and furnishes 145,000 candlepower from a parachute-borne pyrotechnic candle. The shell is 14.28 inches in length, 2.33 inches in diameter, weighs 3.7 pounds, and has four fins spaced about a hollow tail stem which contains the initial ignition char-ge and primer. Nested  in the four fins are pellets of propelling increments in bundles of square powder flake. See Fig. 59. The escape of gases generated by the initiating and propelling charges is provided by 16 vent holes. The Fixed Time Fuze M65 in the nose of the shell functions approximately 14 seconds after the shell leaves the mortar. It expels the candle and parachute, igniting the candle at the same time. The time fuze is held in safety position by a pull-ring safety pin, which is withdrawn immediately before loading it in the muzzle of the mortar.

Figure 59. – Illuminating Shell M83

Operation

149. When ready to fire the 60-mm Illuminating Shell M83, the safety pin is pulled and the shell dropped fins first down the muzzle of the mortar. The loader must withdraw his hands and immediately step back, as the shell slides down the mortar barrel by gravity and strikes the fires pin to ignite the propelling charge. At the instant of firing, a setback element in the fuze ignites the black powder time train in the nose of the shell. This burns 14 seconds and then ignites the expelling charge, dividing the shell and ejecting and igniting the pyrotechnic candle suspended on its parachute. The candle burns for 25 seconds and descends at a rate of about ten feet per second. The ballistic properties of the illuminating shell are markedly different from those of the standard 60-mm service shell. The illuminating shell will thus not illuminate the target of the high explosive shell used in the same mortar at the same elevation.

Packing

150. 60-mm Illuminating Shell M83 is packed in individual fiber containers. Six containers are packed in one outer container, and three outer containers are shipped together, to-taling 18 rounds per bundle. Each shell is painted gray and is marked in black to indicate the type and model, the mortar from which it is to be fired, the filler, and the lot number. The fuze flange on each shell is stamped to indicate the type and model, the manufactu-rer's symbol, the lot number, and the date of loading.

Storage

151. General rules for the storage of pyrotechnic ammunition as given in paragrahs 9 to 12, inclusive, apply to 60-mm Illuminating Shell M83. Misfired or deteriorated shells should be disposed of as detailed in paragraph 17.

Safety Precautions

152. In fiirng 60-mm Illuminating Shell M83, the following safety measures must be taken:

(a) The safety pin in the fuze is to be removed only as the shell is loaded into the mortar and at no other time. Should the round misfire and the shell be removed from the mortar, the safety pin must be replaced immediately.

(b) The shear wire just beneath the safety pin must not be disturbed. This fine wire pas-ses through the fuze and has its ends twisted on the outside. If the wire is broken or missing, the round should be discarded.

(c) Not more than the four propelling increments are to be used under any circumstan-ces.