The founders wanted the militias to provide the bulk of the country’s defense and to not have a standing army. Anyone who owned a gun had to register it so that it could be verified to be in working order in case a militia needed to be formed. That whole idea of having the militia provide for our defense failed pretty quickly when several uncoordinated militias got their asses handed to them by Natives in the Northwest Territory. The federal government moved towards having an actual standing army and the role of militias shrunk.