Construction: This fuze is made of three-piece black steel or brass body. Protruding from the nosepiece is the primary, or impact, striker which houses the secondary or aerial-burst striker. A metal safety clip fits around and holds the striker from the primary pri- mer. The secondary striker within the shaft of the primary striker is held from the aerial-burst primer by a small coiled spring. Housed in the lower end of the primary striker is an aerial-burst primer and a short delay train leading to a black-powder collar which fits around the lower circumference of the primary striker. The explosive train from this collar leads through ports in the midsection of the fuze to the powder time train housed in the midesection. The midsection is movable and may be set for impact firing or aerial burst (2 to 22 seconds).

In the lower fuze section there is one explosive-filled channel, the upper end of which contacts the powder time ring, and the lower end leads to the explosive gaine.

Operation: For aerial-burst firing, the time ring is set and the safety clip removed. On set-back the secondary striker initiates the aerial-burst primer, which in turn burns through the powder time train to the explosive gaine. If impact occurs prior to the lapse of the time set, the primary striker will be driven onto the primary primer. The delay-arm-ing (black) powder collar around the primary striker is designed to allow firing the mortar from a concealed position through underbrush and gives a definite bore safety.

Figure 441 – Type 3 Aerial-Burst-Impact Mortar Fuze.