4mm ETG (preloaded cartrige)

[245Tommy]

I made the first gun out of spare parts, the barrel is three sleeved brass tubes, the electrode is a screw, and the insulator is epoxy mixed with powdered wire insulator. The switch is a 40amp relay with pieces of copper pennies as contacts. It used a 370 joule 660v photoflash capacitor bank (free) with a voltage multiplier to charge it. Ammo is a wad of led or a nail glued to wooden tail wrapped in tape. The soda can full of water was shot at 270J.



The new preloaded cartridge version uses a plastic tube that extends past the center electrode as an insulator, it lasted five shots before it stretched and wouldn't slide in the breech.



lead slug through 22gauge steel



Here's a video with an older chamber design http://www.youtube.com/watch?v=HCZgXYYx5yU
[youtube]HCZgXYYx5yU[/youtube]
[yt]HCZgXYYx5yU[/yt]

[powerlabs]

That is very cool! I am surprized the brass tube held together so well; on my ETC gun I had constant issues with the breech (a spark plug) being pulverized on every shot...

[245Tommy]

I'm still working on this gun, I think the disappointing (under 10%) efficiency is because the discharge time is too long for the 4-6 grain bullets I'm using, unfortunately this is what happens to the plastic tube when I try to shoot a bullet over 9 grains. http://4hv.org/e107_files/public/127...99_400x245.jpg