Construction: The fuze is of one-piece construction. The striker extends from the nose of the fuze into the lower fuze body and is supported by a safety fork which is held in place by a set-back pin. The gaine threads into the bottom of the fuze body.

Operation: On firing, the force of set-back causes the set-back pin to move down against its spring, thus releasing the safety fork. Centrifugal force cause the safety fork to move outward, and, when the projectile clears the bore of the gun, the safety fork is thrown clear of the projectile. This release the striker which is driven down into the gaine on impact.

Remarks: There is a smaller version of this fuze was originally used in the Swiss-made projectiles. It differs from the Model 1 fuze only in size.

Figure 427 – 20-mm Model 1 Fuze.