The last time we tried this, we hit 4600 fps, which is very fast. This time Danny increased the powder load hoping to break 5000 fps.
All the main parts were bought on ebay and the basic design was actually conjured up by Joerg Sprave as an arrow launcher. We are still working on that - having problems as you could see in the intro.
Driving Airsoft BBs Faster than the Fastest Bullet ─ TAOFLEDERMAUS
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