First off, look under the rifle rigth in front of the trigger, there is a small button- hold this button down while retracting the bolt. The bolt will slide free of the receiver. Once the bolt is out of the gun, flip it over and point the nozzle away from you and you will see a rectangular opening behind the rubber gas route, inside it has a large dial (which is a screw running from back to front inside the bolt- known as the PCS dial). By loosening the grub screw inbetween the gas route and the PCS dial, you will be able to turn the dial, and close or open the gas route, changing the output FPS. Alternatively, you can alter the FPS by tightening or loosening the striker spring. to access the striker spring, remove the two flathead screws that are located in the middle of the bolt on the underside. When you remove these screws the bolt will separate into two peices. Now take the cocking handle half and look at the rear on the cocking peice (the part that pops out when the rifle is cocked). On the bottom of the cocking peice is a small grub screw-loosen this screw. Now look to the striker spring that is sticking out of the front of the cocking handle half of the bolt. the spring guide for the striker spring is actually a large screw- face the bolt straight up and down, and either loosen or tighten the spring guide, which will cause the bolt to strike the gas valve on the magazine harder or softer releasing different amounts of gas. Make sure to tighten all of the anchor grub screws and reassemble the bolt in reverse order-this may be a bit tricky, as you have to fight the striker spring to put the two halves together.
Hope this helps, and was intelligible. If not feel free to PM me with more questions.
