Nice mini spud guns
Super glue looks good but can't stand up to any type of vibration or shock like on a mini gun. Hot glue works best for this type thing. ( and I can see you like to use a bunch of it lol)
Now all you have to do is make a small hole in the window screen and bug people who come by
It's really cold here in NJ so ive been starting minis as well.
My first one worked ok but not all the time, I just did a second bigger one similar to your water bottle unit....I can't wait to see how well it works. I'll be firing wire nuts as im an electrician and have loads of them around the house.
medievalman wrote:and another benefit to that is that if the cap blows off, it wont hit you in the balls!

ya mean something like this?
http://my.break.com/media/view.aspx?ContentID=206458
After the first shot, the tube inside burned a bit (smells really bad)
try some silicone tubing. it does not burn as easily and is stiffer so it will be better as a barrel.