Markers, paintball guns, come in a variety of shapes and styles. They may be powered by carbon dioxide (CO2), nitrogen (N2) or compressed air. Many have power systems that use large refillable cylinders called "tanks" or "bottles" that give hundreds of shots before needing to be refilled. Some use small 12 gram CO2 power lets as their power source, each power let being good for 15 to 30 shots.

TYPES OF GUNS

MECHANICAL

Uses a sear, hammer, bolt, and valve to fire the gun
Bolt-action
The very old, original paintball gun. It works like a pump, only it doesn’t have a pump arm to recock it. (no longer made)
Pump
Pull the trigger and the sear releases the bolt and fires a paintball, a pump handle is then used to push the bolt back into a cocked position on the sear.
Stacked Blowback
Most common marker, the bolt is stacked on the hammer, or striker. The hammer is tripped by the sear, and then gas is used to fire the ball. The same gas is used to push the bolt back, which then catches on the sear again.
Inline Blowback
same idea as a stacked blowback, only the bolt is in the same chamber as the hammer.
Hybrid Blowback
Once again the exact same thing; except instead of an mechanical device, an electrical solenoid is used to trip the sear. (aka sear- trippers)
Blowforward
It doesn’t have a hammer, the trigger is pulled and the bolt slides forward, once over the valve it fires the ball. It does not use excess air to fire the bolt back though. (may look similar to an Inline Blowback)
Auto-cocking
A pump with pneumatic cocking rods that will automatically cock the gun. (in other words if you took off the pneumatic rods and put on a pump arm, it would be a pump)

 

ELECTRO-PNEUMATIC

Doesn’t have a sear, uses a solenoid and electro-pneumatics to fire the ball.
Spool
Doesn’t have a hammer or a traditional valve. A sequence of pneumatic controlled rams move air to the ball.
Rambolt
Uses traditional hammer, bolt, and valve. But the hammer is loaded with a pneumatic ram, which will “ram” the valve.

 

CLOSED AND OPEN BOLTS
Closed
Not necessarily the fact that the bolt is covered; almost all pumps are closed bolts because the gun doesn’t cock the bolt. Semi-auto Closed bolts merely cock themselves.
Open
All guns that aren’t closed bolt operation.