What good would a weapon that was not dangerous be? As to being unsual, almost all federal police forces, and of course the US Military, are armed with several different types of machine guns. The Texas Highway Patrol even has boats armed with M249s in shielded mounts.
They have 6 of them in fact.
More info and pictures at this link
Henry also argues that Congress did not have the power to enact § 922(o)’s prohibition against possessing machine guns pursuant to the powers delegated to Congress in the Commerce Clause. That argument fails because we already have held that the Commerce Clause authorizes § 922(o)’s machine gun possession ban.
That's even more idiotic. The Second Amendment is just that, an amendment. By the nature of amendments, they change the basic document where it conflicts with them. The use of the commerce clause, or any other part, such as the power to tax, to infringe on the right of the people protected by the second amendment is thereby forbidden.