Well actually these don't fire from a magazine but a belt. so the restriction is magazine centered. You can't pin a belt. Also these guns do not fire from a single barrel 1 rnd per rotation of the barrels and therefore can't be considered automatic in the traditional sense of the word in our laws.
If you try and import one they will be ITAR, and prohibited from import due to their destructive device classification in the US.
Our laws are so screwed.