The types of weapons, ammunition types, and ammunition capacities allowed by law should be established by Best Practices, as exemplified by the standards of local law enforcement, private security, and top competition marksmen and hunters – never by cosmetic attributes. Basically, whatever equipment the experts deem most appropriate and effective should be available to any other citizen potentially facing the same threats.
Police use AR-15s and high-capacity pistol magazines, so the R+P supports those for private citizens as well. Cops don't generally use M-60 machine guns or fragmentation grenades or flamethrowers, so the R+P isn't going to argue that private citizens should have unrestricted access to those either.