Pneumatic Pnews

Monday, December 26, 2005

Three types of airgun powerplants

by Tex Force

If you are new to airgunning, you may be confused by some of the terms, especially as they relate to how the guns work. This week, I will explain how the different airgun powerplants work, and I'll try to cover at least a few of the common terms.

Pneumatics came first!
We believe airguns were first made in the 16th century, though no examples that old have been found. The earliest air rifle mechanism known for certain is in the Danish Royal Museum. It has a date of 1604 on it, but it is advanced enough to make historians believe that something must have existed earlier.

A very common multi-pump pneumatic today is the Benjamin 392 (third rifle down on the page). An example of a single-stroke pneumatic is Daisy's Avanti 853 Legend (third rifle down on the page).

Three types of pneumatics
The three main pneumatics are: 1) the precharged, 2_ the multi-pump and 3) the single-stroke. The precharged is a gun that stores compressed air for one or more shots. The air is introduced by means of a separate pump or compressed air tank. This is the oldest type of pneumatic mechanism.

The multi-pump came next. This type uses several strokes of a built-in pump to charge the gun. Guns of this type are known to exist from as early as the 1700s.

The single-stroke is a pump-type pneumatic that uses only one pump stroke. If you try to put in a second pump, the first escapes. This type was first offered in the 1960s, making it the most recent.

Spring-air or spring-pistons were next!
This type of airgun does not store compressed air. Instead, the action of a spring powers something that compresses the air on the spot. The earliest type of spring-powered airgun is a bellows guns, where a flat spring rapidly closes a bellows and sends a puff of air up the barrel. You get the same result by rapidly closing a fireplace bellows! The earliest bellows guns are from around the year 1700.

The RWS 24 is a spring-piston air rifle. It isn't pumped, and it doesn't store compressed air. Instead, a powerful spring drives a piston to compress the air when the shot is fired.

Today, however, the most common kind of spring-piston airgun uses a piston with a tight-fitting seal to compress the air. A coiled steel mainspring shoves the piston forward, compressing the air in front of it as it goes. The first spring-piston guns were made in the 1840s. Spring-piston airguns have recoil, plus they have a current top power limit of around 35 foot-pounds.

Then came CO2
Carbon dioxide was first used to launch bullets in the 1870s. The first guns were made in France and were either 6mm or 8mm. The modern CO2 gun was invented by Crosman in the late 1930s. They had to wait until the end of World War II to hit the market. Some survival CO2 shotguns develop over 100 foot-pounds. CO2 develops around 900 psi at 70 degrees F.

Crosman's Nightstalker (second down on the page) is a CO2 rifle. It uses a large disposable cartridge (bottom of the page) that drives the pellet and cycles the semi-automatic action.

Other compressible gasses
Propane is used to power airsoft and now paintball guns. It's marketed as "green gas" and develops just over 100 psi at 70 degrees F. It's good for velocities in the 300 to 500 f.p.s. region but not much higher.

When you buy an airgun, give some thought to the powerplant it has. Each type has advantages and disadvantages - and dictates how the gun functions.


  • actually, green gas is mostly freon. The new Tippmann paintball gun that uses propane actually burns the propane to propell the paintball.

    By Anonymous Anonymous, at 3:12 PM, February 27, 2006  

  • Freon?? That's a brand of chlorofluorocarbon (CFC)... CFCs are banned by the IPPC directive on Greenhouse Gases of 1994. Since they haven't been produced at all in any country since 1994, I doubt green gas is mostly freon.

    By Anonymous Anonymous, at 2:20 PM, June 02, 2006  

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