The Gatling gun is still legal ! U.S. anyway.
a bit complex, but still cheaper than other options and loads of fun !
I see the best ammo option is a .45 acp, lots of plans on the Internet,
Here in the U.S. the Gatling gun is NOT considered a machine gun !
The Gatling is the Grand daddy of the machine gun,
And the updated modern versions ? The GE Mini gun, Vulcan cannon.
You can't beat the simplicity & reliability of the multibarreled Vulcan.