1 Nerf Crossbow
3/4in to 1/2in CPVC adapter
2 8x32 3” machine screws
4 #8 washers
2 8x32 nuts
26 ga. sheet steel
Grinding stone Dremel attachment
Vise or pliers
(*Note: I had already done most of this modification before taking pictures for a write-up. The following steps are listed as if the Crossbow is fully stock at the start.*)
Open up the gun. The first part of this modification deals with the plunger chamber, which is the big yellow piece in the middle of the gun (mine’s mostly black). Disconnect the old yellow barrel and yellow hose from the plunger chamber. You won’t need either for this mod, do with them what you will.
Cut your 3/4in CPVC to 2” and Plumber’s Goop it to the end of the plunger chamber. This needs to dry about 24 hours for full bond. Try to make sure that it is well centered and straight, the 1/2in CPVC needs to be able to fit over the little yellow nub at the end of the chamber.
While that’s drying, you should do basic reinforcement. Cut a piece of sheet steel to the right length and width to sit in front of the spring rest, and use a vise or pliers to bend it to a right angle, and goop it in. Then cut out a slot for the plunger rod to go through, your cut should be flush with the walls.
For the plunger rod, I did this.(thanks to Gengar003) I also reinforced the back of the spring rest with bolts, like Renegade (thanks to you too) did here. I also suggest using a rubber washer behind the head to improve the seal.
Now that your ‘bow is solidly reinforced and your Goop is dry, take your 3/4in to 1/2in adapter and your Dremel with its grinding stone attachment.
Dremel down the ridge inside the piece that stops the CPVC from going through. The 1/2in CPVC should be a perfect fit in it: the pipe should be able to slide into it with little difficulty, but should not be loose enough to fall out.
Now put the adapter on the end of the 3/4in CPVC. The 1/2in barrel should be able to slide in and be very stable, but fairly easy to remove. The 3/4in pipe and adapter provide much more stability than a simple coupler. An 8-9" barrel seems to work best. (All the pictures are with a 12" one but I was still testing when they were taken).
Dremel out all the stuff between the end of the plunger chamber and the opening at the front.
Now you’re done. I find the new coupling system much more stable, but easier to remove than any other system I’ve encountered. I’m in the process of modifying this design to be turret compatible, and will have another write-up in a few days.
It averages ranges in the mid eighties. (with a pair of mini bungees)
Edited by .Z4., 05 September 2008 - 04:37 PM.