Bullet Effects Using Compressed Air

Bullet effects actuated by compressed air are often cheaper than those using wired-in pyrotechnics, but are seldom as effective.

Capsule gun

This takes many forms, but the principle involved is similar to that of the ordinary airgun. A metal barrel containing a projectile is sighted and fired at a target, the projectile being propelled by a charge of compressed air (or carbon dioxide) released through a quick-action valve.

Some of these guns have magazines permitting rapid fire while others comprise a cluster of single-shot barrels each capable of being independently sighted and fired. The magazine types are usually fired ‘from the shoulder’ while the others are more often rigidly positioned.

The projectiles used in these guns vary. Sometimes they are heavy metal slugs to shatter bottles, vases or mirrors while others are fragile pharmaceutical capsules designed to break on impact and scatter their contents over the area of contact. Capsules filled with powder may be used to stimulate the dust caused by a bullet striking rock while, filled with grease, they provide a passable imitation of broken glass.

It is essential to fire the capsules only at hard, inflexible surfaces, because they may pass right through soft materials.

Cycle pump

For a single bullet hit on a rock it is feasible to use an ordinary cycle pump. This may be employed in two ways. One is to bury the end of a flexible tube in a heap of powder, and the other is to suck powder into the pump and discharge it via the tube. Both will give a swift spurt of dust which, when combined with a dubbed sound effect, will look remarkably convincing.

The advantage of using this type of effect is that, unlike a bullet hit, it can be positioned very close to an actor’s face.

If the operators can be hidden, cycle pumps can be used with equal effect in long shots. Fuller’s earth or cement powder is invariably used for this trick.

BULLET EFFECTS USING COMPRESSED AIR

1. Single barrel compressed-air gun
Also known as the capsule gun. a, Solenoid valve, b, Control button, c, Compressed air. d, Battery.

2. Metal projectile
a, Projectile, b, Skirt made from adheisve tape. The skirt expands in the barrel to form an airtight seal.

3. Gelatine capsule projectile
Both types of projectile are loaded via the barrel and pushed down with a rod. The gelatine capsule needs a wad of cotton wool behind it.