A mod to increase the power / range of the gun.

Print part
Remove barrel extension
Remove bolt
Remove all external screws on the main gun (not the stock)
Unscrew the two screws holding the spring holder (right hand end of the spring)
Use printed part inside the spring holder
(Optionally - drill out air restrictor / valve from the right hand end)
Reassemble
Fire further

A photo of the internals is an easy find on the internet:
http://modworks.blogspot.com/2010/01/nerf-longstrike-internals-guide.html