Paint ball gun with automatic percussion controller

A paint ball gun, comprising a first chamber, a second chamber parallel to the first chamber, a barrel connected to the first chamber, a percussion member received in the first chamber for reciprocation, an aperture communicating the first chamber and the second chamber, a valve mounted in the second chamber and at an end of the aperture, a rear plunger at an end of the second chamber for reciprocation, a firing member received in the second chamber between the rear plunger and the valve and connected to the percussion member, a spring received in the second chamber between the firing member and the valve, a handle adjacent to the second chamber, in which a trigger assembly is provided, and a percussion device mounted where the second chamber is communicated with the rear plunger;

• wherein the percussion device has a base, which has a chamber therein, an inlet communicating the second chamber with the chamber and an outlet communicating the rear plunger with the chamber, and a guiding block and a rotator are received in the chamber of the base;
• wherein the guiding block has a resting end rested on a resting end of the rotator and has a first tunnel with an end open at the resting end and an end communicated with the inlet and a second tunnel with an end open at the resting end and an end communicated with the outlet and the rotator has a storage chamber therein and a first bore and a second bore with ends open at the resting ends thereof and ends communicated with the storage chamber, whereby the rotator is rotated by a driver to selectively align the first bore of the rotator to the first tunnel of the guiding block or align the second bore of the rotator to the second tunnel of the guiding block respectively.