Currently investigating the feasibility of powering a BB gun with Hydrogen/Oxygen mix. So far so good. Now I only have to design a machine gun around the ammo.....
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I totally agree!
However, the compressed air MG is designed with DIY-ability as priority no1. The only "exotic" materials needed are the nylon worm gears that comes with the book. The simplified version on the other hand needed a very-difficult-to-find barrel made of high quality stainless steel ...

I have been experimenting with a simpler setup as well.
Ironically, the simpler version had long time reliability issues.
Different parts of the BB feeder system were dented by handling the BBs at elevated speeds (barrel striking back and forth).
Never the less, I admire you for your great ...

:D


So the barrel is forced/accelerated backwards trough the coil, closes the breech and hits the valve in the back of the loading-mech?
Correct!

Do you drill out this piece from the top after soldering it together?
Yes, and you better be careful while doing it!


Is there a spring in the ...

Brilliant analyze, spot on!
I’m so sorry to hear about your eye cancer...it was totally unintentional on my behalf.....:lol:
I have been passing by as a guest from time to time and always been mighty impressed by the positive spirit and enormous creativity in the spud files forum.

The video clips ...

Thought this might be of interest for other as well:
BB machine gun based upon a 2kg fire extinguisher.



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