aiea7 wrote:  "hence, there should not be any constitutionally right to own a gun"
I understand that you want that to be true, but it is not.  
"The Second Amendment to the United States Constitution protects the right of the people to keep and bear arms ...". The Supreme Court of the United States has ruled that the right belongs to individuals.
https://en.wikipedia.org/wiki/Second_Amendment_to_the_United_States_Constitution
It is designed to deter tyrannical government.  Has the U.S. government ever locked up its own citizens for no crime?
☑ Manzanar 
☑ Honouliuli 
Has the U.S. government ever shot its own citizens dead for protesting? 
☑ Kent State