FM 23-11 90MM RECOILLESS RIFLE, M67

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**22. Fuzes, PIBD, M530 and M530A1.
a. A fuze is a device used with a projectile to explode it at the time and under the circumstances required.
***b. The M530 fuze is point-initiating, base detonating with an inertially operated graze system. The
fuse is armed by setback forces through a delay system. On impact, a piezoelectric crystal in the nose
spike is crushed and generates an electric current that is transmitted by wire to the fuze. The graze system
insures detonation regardless of the angle of impact. The M530 fuze is assembled with a booster. Due to
its location in the projectile, the fuze is not visible in assembled rounds of ammunition.
**c. The M530A1 fuze is a modification of the M530 fuze. The M530A1 fuze has a mechanism which