Let's say there is no constitution.
Can you decide, that I may not have a weapon to defend myself? Where did you get the authority?
Can I or anybody decide that you must not have a weapon to defend yourself from tyranny, be it a thief, a murderer, a rapist or government etc.? And if we can do that where did we get the authority?
And if you, nor I, nor anybody else has no right to say that another human being can not, or must not have the means of protecting against tyranny where does government get the "right" then?

I believe no one can take the means of protection against tyranny from anybody else. Constitution or laws don't change that i.m.h.o. :)

Peace