First, ope it up

It's so nice and simple.
Insert a piece of thin wall pvc into the front part of the plunger assembly and secure it. (I did this with a bit of E-tape) This will reduce the dead space inside.

Also, put in a dart stop at the back end.
Now for the breach/barrel.

Take your barrel material (i chose CPVC, 18 inches) and use another pipe that is tight around the barrel material and place 1.5 inches of around the barrel. Now, cut a notch near the back where you can easily insert a dart. tape off the back with a bit of e-tape (as a dart stop).
Now, take your barrel and fasten that smaller section of pipe and nest it tightly on the outer part of the front plunger assembly.

Now, put the gun back together, including four bungies, and you are done.

Some close ups of the breach: Open

Closed

Thanks for reading!
Video
Edited by koree, 28 February 2010 - 10:58 AM.