Kyle and the boys were here last night, and Zachary asked me if I could build a popgun.   My first thought was no, I didn't know where to get the spring or how would I make a sear.   But, Kyle sent me pics of the popgun at Bucees and I realized, no spring and no sear, this I can do.   The barrel fits around a plunger that is attached to the stock.   When the barrel is moved quickly back toward the stock, air is compressed in the barrel and the cork "pops" out the end and is stopped by the string.   The barrel must be long enough that the cork doesn't come in contact with the plunger when the barrel is back against the stock.

NOTE: The end of the white PVC barrel (2 or 3") must be painted bright Orange or Yellow to conform with Federal requirements.    

Nuther Note: I am working on a better end for the 5/8 dowel plunger.   I will attempt to make a wooden collar that will be a snug fit inside the 3/4" barrel.