I know you can not use Electric Motors but would steam/gas engine be legal?
What? Go to bed. You can’t handle the late nights.
If you’re really that desperate to blow through ammunition you could always just dump a case of .223 in a bonfire and watch it from a safe distance.
Probably about as risky as hooking up a steam engine to a Gatling gun.
And also legal.
There’s at least two studies showing the viability of steam if you just use the search function. The second study however including a water wheel clearly shows it’s superiority.
No. According to ATF, hand cranked Gatling guns don’t fall under the NFA because they’re muscle powered. Essentially ATF regards the crank as the trigger, so the gun will not continue to fire without further action on the “trigger” by the operator. However, once you add any sort of mechanical device to turn the crank it’s a machine gun.