Private ownership of firearms is an important aspect of separation of powers. It keeps the true power in the hands of citizens rather than in the abusive hands of government agents.
Where there is any sort of private gun ownership, it checks government power because the government knows that the citizens may resist should there be a tyrannical regime.
Where guns are banned for private citizens, the government usually has malicious intent as history shows.
Americans tend to know this, and they are buying guns in massive quantities, making any more gun control laws all the more impossible to enforce. But you know what else? Crime is plummeting.