This mod will increase the effective range of the nerf firestrike, along with give it the ability to accept different barrels and speedloaders, for which there will be a tutorial coming up for soon! Once again, this is a "how I did it" mod meaning I have already modified the gun and am just going over the internals.
Step 1: Le Internals
To reach the guts of this blaster, simply unscrew all the screws using a Philips head screwdriver and then remove the half of the shell that has the screws in it. On the first picture, you can seek have faked out the stock barrel and added my own. To do this, take out the barrel entirely. There will be a few sections of the barrel. Remove the last one and take out the pegs holding the middle structure in place with a flathead screw driver and hammer. Then sand out the inside and put a 1/2 in cpvc coupler in. Add a very small piece of cpvc to the end of it and attach a second coupler. Then use some electrical tape to seal up any air release holes. The pictures of the barrel shown should give you an idea of what is going on.
Step 2: Plunger and Plunge Tube.
This shows you I have use electrical tape to buff up the o-ring, and also added a maverick spring. To do this, wind the maverick spring around the plunger. This is pretty simple.
Step 3: Getting It Back Together
You should be able to see the peg I sanded down. This is to allow the barrel I installed to fit. I also sanded out the inside of the barrel so the cpvc barrel can fit through. That's it.