A spring powered system uses a spring that is inside an air tube. The spring is attached to a piston. When the rifle is cocked the spring and piston are drawn back and locked at one end of the air tube. The other end of the air tube has a small hole that is directly behind the pellet and rifle barrel. When the trigger is pulled the spring is released and it pushes the piston down the air tube forcing all the air through the hole, and that fires the pellet down the barrel.
Take a tube, put a piston in it, seal off both ends of the tube, and use a liquid, or gas to put pressure in and remove pressure from the tube. As the fluid or gas goes in the tube, the pressure pushes the piston out. As the pressure is released, the piston can recede.
Because of the small design of a BB gun it is not possible to change the air system. However if it's a pellet springer rifle, not a BB rifle, then in some cases it is possible to change it with a Nitro piston system. But this should be done by a professional air gun service. A nitro system replaces the spring piston with a gas piston tube. It usually cost around $130.
a piston pin is a machined high strength steel "tube" that goes thru the piston and connecting rod and holds them together.
Their are 4 common types of air rifle power plants. Spring power: or Nitrogen piston power. this uses a large spring inside an air piston tube; When the barrel is cocked (Commonly called a break barrel rifle) the spring is pushed back in the piston chamber and locks. A pellet or BB is loaded. When the trigger is pulled it releases the spring, forcing the piston forward in the air piston chamber, Compressed air fires the pellet out the barrel. C02: a C02 cartridge is loaded into the rifle and acts as a small air chamber releasing some C02 each time the trigger is fired. Eventually the C02 is used up and has to be replaced. Pump power. simply you pump the forearm on the rifle and it fills an air tank. When you have enough compressed air you fire the rifle PCP: Pre Charge Pneumatic: This is a large air tank inside the rifle. It is charged with a bicycle pump or scuba tank. It's like an oversized C02 tank inside the rifle. Again each time the trigger is pulled the tank releases a burst of air behind the pellet to fire it out of the barrel. This type of air rifle is usually a very high-powered rifle.
A piece of small tube
The Bore of an engine is the tube that the piston goes up and down in.
Most spring Pellet guns should not be dry-fired. When you shoot a spring powered air gun or rifle, the spring compresses the air in the airtube and the compressed air forces the pellet out of the barrel. The compressed air also slows down the spring piston due to the air being compressed. In this way the piston doesn't slam against the end of the chamber. When you dry-fire the rifle without a pellet in the breech the piston has no resistance in the chamber and slams against the end of the airtube. Eventually it will ruin the air tube and the rifle or gun. If you dry-fire a C02 gun nothing will happen no damage will occur.
A twin-tube damper consists of two concentric tubes with the inner tube containing the piston and valve assembly while the outer tube acts as a reservoir for the hydraulic fluid. When the piston moves in response to vehicle suspension movements, hydraulic fluid is pushed back and forth between the two tubes through the piston's valves, controlling the rate at which the suspension moves and providing damping to control bounce and jounce.
Best left to a trained gunsmith.
Markham-King 21-33 made 1933-35 .177 caliber, fired lead shot or darts. It had a removable shot tube. It was a single shot powered by a spring piston. It was marked KING MFG CO.
The Sleeve is the tube that covers the REAL barrel on the rifle. It protects the barrel from damage. It's nothing more than a hollow tube surrounding the real barrel inside.