I don't really have to define 'effective' because the thing I'm responding to is a bit of pat mythology to try to sort-of-explain something complicated and unclear like 'Why does the US Constitution have this weird 2nd amendment and what the hell does it mean?'. It's a shorthand, not a real thing, think of things like 'not a democracy, a republic', etc. There's obviously no simple direct connection, historically, statistically, whateverlly, between who has guns and how government works. People who get upset enough with their government to want to violently remove it with guns just get the guns or convince the people with the guns to join them, etc. Nobody sits around around pondering "boy, we'd start a movement of dissent but we won't because none of us are packin".