Yes, you *can* own a minigun / Gatling gun...

[Grenadier]

...lawfully, that is! This guy even has the BATF papers to certify its lawful status.

http://gatlingguns.com/indexframeset.html

As long as it's hand-cranked, you're not creating a firearm here (you're simply *lawfully* modifying two such firearms).

You can even make your own with two AK-47's...

http://gatlingguns.com/akfortysevenkit.asp

[Big Don]

While it would probably be a lot of fun to play with. I'd much rather keep my weapons in normal, that is designed working order.