Airgun rifles are classified based on their power source, mechanism, and purpose. Here are some common types of airgun rifles:

1. Spring-piston air rifles: These rifles use a coiled spring and a piston to compress and release air. When the trigger is pulled, the released air propels the pellet or BB out of the barrel. They are popular for their simplicity and affordability.

2. Pre-charged pneumatic (PCP) air rifles: PCP rifles use a pre-charged air reservoir (usually filled with a hand pump or a scuba tank) to provide the air pressure needed to propel the pellets. They offer high accuracy, consistency, and multiple shots before needing to refill the air reservoir.

3. Gas piston (Gas Ram) air rifles: These rifles use a gas-filled piston instead of a coiled spring. When the trigger is pulled, the gas expands and drives the piston forward, compressing the air in the chamber and launching the pellet.

4. CO2-powered air rifles: These rifles use small CO2 cartridges to power the shots. The CO2 gas is released when the trigger is pulled, propelling the pellet. CO2-powered rifles are easy to use and are often used for recreational shooting.

5. Multi-pump pneumatic air rifles: These rifles require the shooter to manually pump the air into the compression chamber before each shot. The number of pumps determines the power of the shot.

6. Break-barrel air rifles: A popular type of spring-piston air rifle, these guns have a barrel that pivots on a hinge. To cock the rifle, the shooter must "break" the barrel downwards, compressing the spring, and then close it to load the pellet.

7. Side-lever and under-lever air rifles: These rifles have a lever located either on the side or under the barrel that the shooter operates to cock the gun and prepare it for the next shot.

8. Lever-action air rifles: Similar to lever-action firearms, these air rifles have a lever mechanism that reloads the gun after each shot.

9. Bolt-action air rifles: Modeled after traditional bolt-action firearms, these rifles require the shooter to manually operate a bolt to load a pellet into the chamber.

10. Fully automatic air rifles: These rare types of air rifles can fire multiple shots with a single pull of the trigger, but they are subject to strict regulations in many regions due to their potential for misuse.

Remember, the availability of certain types of airgun rifles might vary depending on local laws and regulations, so it's essential to research and abide by the laws in your area.