Why is that needed? It is the 2nd Amendment.
The Federal Constitution and Federal Bill of Rights did not repeal the state Bills of Rights. This is acknowledged at the Constitutional Convention.
Mr. SHERMAN, was for securing the rights of the people where requisite. The State Declarations of Rights are not repealed by this Constitution; and being in force are sufficient.
https://avalon.law.yale.edu/18th_century/debates_912.asp
Iowa needs an Amendment of this effect because as a jurisdiction, Iowa is vulnerable.