A hand crank, manual fed weapon is legal according to the feds, but state/local regulations should be checked as well. A local has a fancy brass Gatling in .45-70, as he explained it to me, each crank constitutes a pull of the trigger. The issue with them is "bump firing", it can be done, and as soon as you mount said "motor" it becomes a true machine gun. That is where the big issue starts, it's legal one way, stupidly illegal the other.
The orginial hand crank Hotchkiss machine gun is in the same status, legal by federal standards. State and local laws may affect it as well.