Use: H.E. projectiles for the 81-mm, 90-mm, and 150-mm mortars and incendiary projec-tiles for the 90-mm mortar.

Over-all length (with gaine): 3 13/16 inches.

Over-all length (without gaine): 2 13/26 inches.

Maximum diameter: 1 1/4 inches.

Threaded length: 1/2 inch.

Number of threads: 5, left-hand.

Construction: The brass fuze body is made is made in two major parts joined togehter by (right-hand) threads. A housing, containing the firing pin and a movable primer, is press-fitted into a recess in the upper fuze body and supported by a shear pin. The firing pin and movable primer are separeted by a coiled spring. The primer is held from the firing pin by a metal washer with two ears 180° apart. These ears fit into longitudinal slots in the lower part of the firing pin housing and rest against the under side of a shoulder in the upper fuze body. The gaine threads (left-hand) into the lower fuze body.

Operation: On impact the shear wire is broken and the lower part of the firing pin hous-ing is driven down into a recess in the upper fuze body, thus freeing the primer to move forward onto the firing pin. The choice of instantaneous or short delay is made by un-screwing the upper body and inserting or removing a delay pellet.

Figure 325 – Type 93 Instantaneous-Short-Delay Fuze.