Step 1: Gather Your Materials
4 inch piece of CPVC
4 inch piece of PVC (make sure the CPVC can fit inside the PVC snugly. if it does not easily fit in, sand down the outside)
Dremel with sanding bit ( you can also use a drill with a dowel wrapped in sand paper to make a make-shift sanding bit.
a Nerf gun with a PVC coupler
Step 2: Sand out CPVC
Step 3: Put the two pieces together and fire
Step 4: How an inline clip works
If is not a good explanation, please ask me to edit this and make it better.