Bertha
Posted: Sun Aug 05, 2007 7:45 pm
We call her Big Bertha, for lack of a better name. And it stuck.
This gun was a joint project between myself and some of my good friends, pictured here.
The barrel is 6' of 1.5" sch40, chamber is 4' of 3", and it has a homemade piston activated by a modded sprinkler valve. It's my biggest project to make, but it went together fast b/c we planned it out.
The piston is made out of 1.25" couplers and endcaps, which allows for easy o-ring grooves. The tee is 2". Notice that the barrel unscrews from the gun to allow access to the piston: I think this is the first gun to use that. The barrel just barely passes thru the 2" male threaded coupler. I thought it would be safer this way than having a threaded fitting at the rear of the piston, since I've had threaded coupler breaks on me twice on smaller guns, once resulting in a nice solid blow to the chest!
I've got no way of gauging the range, esp b/c the potato goes out of sight not long after it reaches the peak of its trajectory. It has quite a kick, even without ammo it still is noticeable. We generally have two people holding it to fire. The best damage we got was a 4" hole in the bark of a big oak tree, plus sticking some large bolts thru old computers.
This gun was a joint project between myself and some of my good friends, pictured here.
The barrel is 6' of 1.5" sch40, chamber is 4' of 3", and it has a homemade piston activated by a modded sprinkler valve. It's my biggest project to make, but it went together fast b/c we planned it out.
The piston is made out of 1.25" couplers and endcaps, which allows for easy o-ring grooves. The tee is 2". Notice that the barrel unscrews from the gun to allow access to the piston: I think this is the first gun to use that. The barrel just barely passes thru the 2" male threaded coupler. I thought it would be safer this way than having a threaded fitting at the rear of the piston, since I've had threaded coupler breaks on me twice on smaller guns, once resulting in a nice solid blow to the chest!
I've got no way of gauging the range, esp b/c the potato goes out of sight not long after it reaches the peak of its trajectory. It has quite a kick, even without ammo it still is noticeable. We generally have two people holding it to fire. The best damage we got was a 4" hole in the bark of a big oak tree, plus sticking some large bolts thru old computers.