Create three categories of “arms”: Personal Defense, Hunting, and Assault.
Each State may enact the laws it wishes to provide for a “well regulated militia”, and that may have Assault arms per that State’s militia laws.
Rules that States may enact include but is not limited to: #1- Joining the militia is only receiving an ID card from the State. #2- Creating mandatory training exercises. #3- Charging a fee to be a member. #4- All or certain Assault arms are to be kept in a defined secure manor, or even in an official militia armory.
For Personal defense, hunting arms: The public should be allowed to own a reasonable number of arms. All Purchases are subject to background checks, and any other regulation reasonable to stop the dangerous from possessing arms.