How an Autococker works

The Autococker fires from a closed bolt. It is probably the only gun that fires closed bolt. The auto-cocker system only activates during the last half of the trigger pull. The final portion activates a three way valve that allows CO2 to enter the front side of the activating cylinder. This in turn pushes the cocking block backward approximately 1″ and moves the bolt and cocking rod backwards. At this time the hammer latches and a paintball drops into the breech. The bolt and cocking assembly remains in the rearward position until you release the trigger. Releasing the trigger reverses the three-way valve. This vents the CO2 from the front of the activating cylinder and routes CO2 to the rear of the activating cylinder. The cylinder then pulls the cocking block and bolt into the forward position. The gun is now ready to fire. The first half of the next trigger pull releases the hammer, firing the gun, and the second half of the pull repeats the above steps.

Or in other words…

The basic idea behind the Autococker is to take a pump gun and replace the pump handle with a piston to pump the gun automatically. Hence the ram. The ram is controlled by a 3-way valve that is connected to the trigger. The ram, 3-way, and regulator are located under a cover or exposed (most are exposed) on the front of the gun. The cocking block connecting rod run down the left side of the body. It connects the ram to the cocking block. When the trigger is depressed, the 3-way sends Co2 to the back of the ram’s piston and it in turn pushes the cocking block back. When this happens, the block pulls the bolt and cocking rod back as well. The bolt is now open which allows a paintball to fall into the chamber. The cocking rod is connected to the hammer, so the hammer is also pulled back until the sear catches on the trigger. When the trigger is released, the 3-way routes CO2 into the front of the piston, pulling the cocking block forward, closing the bolt. The paintball marker is now ready to fire. Depressing the trigger again fires the paintball and begins the cycle again.
So the Autococker will not fire a paintball on the first trigger pull, but rather has to cycle a paintball into the chamber first.