Bullet squib

Bullet hit Squibs are used in motion pictures and television to simulate ballistic impact of fired projectiles. 

A device used as a primary stimulus component in all explosive or pyrotechnic devices, such as detonator primer or squib, which, on receipt of proper mechanical or electrical impulse, produces burning or detonating action. Generally contains a small quantity of sensitive explosive (-> Squib -> Detonator -> Primer -> Bullet Hit Squib). 

Frequently, specially designed fireworks are used for creating these effects, e.g. tiny detonators (-> Bullet Hit Squib) for the simulation of bullet impacts. )... 

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