Airsoft guns are remarkably realistic toy guns modeled after popular firearms. They are designed to fire pellets at a low enough velocity they will not hurt a person and certainly won't break skin, but the power can be turned up a bit in most cases. There are three types of airsoft guns: spring, electric and gas. Gas guns are designed for power adjustment already, whereas spring and electric guns will need adjustments to increase the power.
Carefully examine your gun and its manual to determine if your airsoft gun is of the spring, electric or gas variety. Your manual will say for sure, but you can easily tell an electric gun by its battery compartment hatch. Distinguishing a gas gun usually requires you to remove the clip and look for a small gas valve inside, which is similar to an air valve on a tire.
Review the manual if you have a gas-powered airsoft gun. The good news about these guns is that they're designed to have the power adjusted, so there's no need to alter the gun in a way that would void the warranty. However, the specific procedure for adjusting the power varies among all the different gun styles. It's usually a simple matter of turning a hidden dial or screw, but to locate this adjustable component and find out exactly how to manipulate it, obtain instructions from the manufacturer specific to your gun model.
Examine the outside of the gun if you determine you have an electric- or spring-powered model. Look around the outside of the gun for screws. Count them and note their locations; you'll need to remove them all and reinstall them later. You should also take note of the seams in the plastic body of the gun; you'll soon be pulling apart the two molded halves. Since airsoft guns are somewhat complex devices, you should be as prepared before taking one apart.
Remove all of the structural Phillips head screws and set them aside. The exact number of screws and their locations vary among gun designs, but all of the screws should be easy enough to spot.
Lay the gun on a flat surface on its side. Apply slight downward pressure on the top side of the gun with one hand to steady it and hold the two molded halves of the gun together. With your other hand, get a firm grip on the bright orange tip on the barrel of the gun and pull it off. This is the most difficult part. Removing the tip may require lots of pressure and twisting, but too much force can break the gun. If you aren't getting anywhere with your bare hand, try prying at the gun with a flat head screwdriver. Keep in mind the tip is all that is holding the gun together at this point. It is important to support and hold together the gun when the tip comes off.
Steady the gun on the flat surface after the tip has been removed and pull off the top half, slowly and carefully. Take your time here because there are springs on the inside that may pop out if you handle the gun too roughly.
Locate the plunger and firing spring. These will be toward the back of the gun and directly behind the end of the barrel. When you cock the gun, the plunger moves toward the back of the gun, compressing the spring. This creates the energy needed to fire the pellet. Grab the plunger with your fingertips and manually pull it to the back of the gun as far as it will go. You'll notice it doesn't go back far enough to fully compress the firing spring. If you set up the gun so this spring will fully compress, you'll get more power.
Allow the plunger to return back to its normal resting position. Stack the metal washers together. Use your fingers to partially compress the firing spring without touching the plunger. This will create space between the back of the plunger and the front of the firing spring. Slip the stack of washers into this space.
Pull the plunger all the way back again to see how much more the firing spring compresses. If there is still room for it to compress more, and you want to maximize the power, estimate how many more washers it will take to compress it all the way. Repeat the previous step to add the additional washers.
Place the top half of the gun body back on the gun and press it into place. Make sure the seams line up perfectly all the way around. Stick the orange tip back on the barrel. Push it on hard.
Replace all of the screws you removed earlier. Your airsoft gun is now powered up.
Opening your airsoft gun voids the warranty. Spring and electric airsoft guns are not designed to have their power levels changed. When playing with airsoft guns with friends, make sure everyone wears full eye and face protection. Even a powered-up airsoft gun will fail to break the skin with a shot, but the pellets can cause eye injuries or accidentally enter mouths or nostrils.