Abstract: In a weapon subject to a sequence of high acceleration followed by high spin and including a detonator and an explosive charge; the improvement comprising a barrier located between the detonator and explosive charge to normally form an obstruction to prevent accidental detonation of the explosive charge by the detonator. Mechanical locking means are provided to lock the barrier in place, comprising a spirally wound ribbon, a pair of pins restraining the outer surface of the ribbon to prevent premature unwinding, and a pair of superimposed anti-friction balls mounted on a hub portion of the ribbon, the upper ball being seated in an extension portion of the barrier. When the weapon is fired from a gun, the high acceleration will remove the pins and allow the ribbon to unwind. Upon unwinding the entire ribbon, the balls will be released and the barrier under the action of spin, will be removed to provide an unobstructed path between the detonator and explosive charge.