The Second Amendment to the Constitution clearly states:
A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed.
The "Reserve Militia", legally defined as all able-bodied men ages 18-45, cannot own any fully automatic firearms, unless they are manufactured and registered before 1986. This is a direct infringement of the right to bear arms.
There are under 200,000 legal fully automatic firearms owned by civilians, and only one has been used in a murder. The only other documented murder with a legal automatic weapon was committed by a police officer. Handguns contribute about two thirds of the murders with firearms, and remain undoubtedly constitutional, as recently made clear by the Supreme Court.