make it being shot faster
cutting out the air restrictor does work best
instead take the air restrictor out of your gun and youll have alot more power!
I have an instructable on it. Type in zack attack and find me and go to my instructable.
To shoot faster you make the dart lighter - but they're so light that this method doesnt actually net more energy - because force is a function of mass and acceleration (essentially speed)... You want to mod the GUN to output more air to push the round harder - easiest method is to add/replace the spring with a bigger one - they mostly all operate on the same principle - a spring loaded chamber is cocked then the trigger releases the energy in the spring pushing a piston into a cylinder. The air in the cylinder shoots the dart - more spring = more air pressure. If you want more force, you can add mass to the darts also - it will go slower (same overall energy) but more penetrating power. Add a few pennies to the suction cup of the dart with some electrical tape and see what happens. DO NOT SHOOT WEIGHTED ROUNDS AT PEOPLE/ANIMALS/EXPENSIVE THINGS.
a few pennies is way too much. they just fall out of the gun. Search for an instructable for it.