How does an air rifle work?

I find many new air gunners asking, “How does an air rifle work?” That’s natural! To think of how air can power a rifle is mind-boggling enough.  Even more questionable is how such a rifle can kill an animal as big and tough as the Cape buffalo.

How does an air rifle work

Well, the doubts will cease once you understand the operating mechanisms of air rifles. Here we go!

The general operation of an air rifle

Speaking generally, air rifles make use of compressed air which is known to have high pressure. There are different ways of compressing air, as we shall soon see after this section.

The general operation of an air rifle

Once you load the air rifle with ammo, all you have to do is pull the trigger to release the compressed air. The pressurized air is released into the rear end of the barrel of the gun, where the ammo sits. The ammo is therefore forcefully driven along the barrel and out into the air.

This fairly summarizes the basic operating mechanism of all air rifles. The difference comes in the powerplants. There are 5 main types of air rifles based on the powerplants:

  • CO2 powered air rifles
  • PCP air rifles
  • Spring-powered air rifles
  • Gas piston air rifle

CO2 Air rifles

CO2 air rifles are powered using Carbon Dioxide gas. This exists in the gaseous form at temperatures above -69.9 degrees Fahrenheit. Increasing the temperature of Carbon Dioxide to 70 degrees Fahrenheit while confined to a vessel, the pressure increases to 852.8 psi. Any extra CO2 in that vessel takes the liquid form. 

CO2 Air rifles

As such, the CO2 cylinders usually contain pressurized CO2 above liquefied CO2. A single shot releases a small portion of the CO2. Some of the liquefied CO2 in the cylinder turns to gaseous form until the pressure stabilizes depending on the current temperature.

Therefore, the pressure in the CO2 cylinder remains fairly constant until all the liquid CO2 turns into a gaseous form. 

It is worthwhile to note that the pressure within the CO2 cylinder simply depends on the temperature and not mechanical compression. Your CO2 air rifle will therefore have more pressure on hot afternoons than when the weather is chilly  

PCP air rifles

Contrary to CO2 air rifles, PCP air rifles used compressed air – the general breathable air. The pressure within the air cylinder depends on the degree of mechanical compression, and not on temperature as seen in CO2 air rifles.

PCP air rifles

The degree of compression achievable depends on how the air cylinder is built, in terms of the maximum fill pressure. Some air cylinders can accommodate as much as 3500 psi, while others hold less than 2000 psi. 

Every shot decreases the pressure in the air cylinder. After several shots, the pressure falls to a level that cannot sustain powerful shots. This tells you it’s time to recharge the PCP air rifle. You may do this using the manual hand pump or the scuba tank. 

Spring-powered air rifles

These air rifles basically use a helical spring. The spring has a piston in front of it. 

Spring-powered air rifles

There are two variations of this:

  • The break barrel – you have to swing the barrel along a hinge so as to load the ammo and cock the gun
  • The fixed barrel – The barrel can’t swing, and so the air rifles come with a separate cocking lever. This can be located under the barrel or to the side of the barrel.

Cocking the air gun results in the mainspring being compressed. It is this elastic energy stored in the compressed spring that powers the gun. By pulling the trigger, you ideally release the compressed string, forcing it to violently push the piston in front of it. This additionally pressurizes the air in front of the piston. The pressurized air forces the pellet to fly along and out of the barrel.

Gas piston

This operates in a very similar fashion to the Spring-piston air rifles. But instead of compressing a helical spring, you compress a gas. The gas, in this case, can be nitrogen, which has favorable properties that make it usable in air rifles. That is the reason you hear of Nitro Piston air rifles. When you pull the trigger, the gas expands and forcefully pushes the piston forward.

Conclusion

All these air rifles have their related pros, cons, uses, and costs. To get a deeper insight into how air rifles work, visit Air Gun Maniac and check out their detailed guide on how to choose the best air rifles on the market