Use: 25-mm H.E. projectiles.

Over-all length (with gaine): No data.

Over-all length (without gaine): 1 3/16 inches.

Maximum diameter: 3/4 inch.

Threaded length: 3/16 inch.

Number of threads: 6 R.H.

Construction: The fuze is constructed of brass in two pieces, with the upper or nose-piece threading onto the main body. In some cases the nosepiece has been found to be made of steel. The striker extends from the nosepiece into the lower fuze body and is supported by a centrifugal detent. The gaine is threaded into the lower fuze body, with its uppermost part just below the striker point. A lead azide pellet is embedded directly below the primer in the gaine.

Operation: After firing, centrifugal force moves the detent out, arming the fuze. On im-pact, the striker is driven into the gaine, causing the fuze to function.

Remarks: This fuze differs from the type 1 in that its nose is more sharply pointed, the striker is longer, and the flash-hole shutter and housing are eliminated.

The type 4 fuze fits into a smaller cavity, and thus there is a larger amount of filling in the new projectiles.

Figure 432 – 25-mm Model 4 Fuze.