@seeking9006: 30meter Rangefinder: some of the laser tape measures out there might be suitable. I seem to recall that several have 120' (~35m) measurement ability (brands escape me ATM. . . look in the back issues of "fine homebuilding" for 2007 or 2008.) an online article that might yield some lead...

Don't spring the rails! Even if you can get accurate machining to do so. Those cables that separated, even though they were zip-tied? Same thing will happen to your rails, making contact-pressure lower and rail/projectile erosion worse. In fact, shorten those cables as much as you can, twist them t...

Sorry for the bump, but: From someone who has actually worked on a railgun trying to record various parameters, some of which had to be picked off the rails themselves, consider the following: Muzzle flash is significant. I made several video takes where the flash inside just the breech shows the in...

PVC is brittle at all temperatures. . . it's a question of how hard you have to hit it before it shatters. Proof? I've shattered multiple pieces of 1.5" SCH40 while using it as carpet beaters on a summer afternoon. Of course, I was a mite annoyed to be beating carpet in the first place, so I was wor...

Air cylinders (rams) will work. for a while. As you've already realized, the problem is not pressure, it's heat. . . . combustion engines are more properly called "heat" engines. . . which includes internal and external combustion, piston, turbine and other types. Some of that heat will 'soak' into ...

First things first: Hi, everyone. . . been lurking for a few weeks. To business: the piston/barrel seal in this design is a ROYAL pain. . . . 6 years ago, I built an all-metal (aluminum and steel) artillery-loading version of this idea, firing soda cans/tennis balls. (150PSI max, 10ft BBL, 8 rnds/mi...