Likely you will find much better explanations than I can offer, but from what positions you've carved out, it doesn't appear that this NAP philosophy is your foe, only that you don't adhere to it because it limits the means (using guns to remove guns) to your desired end (less guns). So even if your position is rational, it is also immoral.
I believe this is the #1 point; if one has any desire for violence as a moral and legitimate means to solve non-violent problems, NAP makes no sense whatsoever. The moment someone identifies the center of any society, politics, as a violent means to solve both violent and non-violent problems, the NAP becomes both plausible and preferable, and thus the libertarian standpoint is to replace the aggression at the center of society with non-aggression: I predict, once this occurs (and can only occur in the individual, never in politics), the violence we experience throughout the world, stemming from our current violent center of society, will change to peace experienced throughout the world, stemming from a peaceful center of society.
This is why authority is on the exact opposite side of the spectrum; authority is always backed with violence, and those who seek peace in this world will never find it through the libertarian polar opposite, authoritarianism, e.g. the state. So, to seek peace, we must be peaceful, and many of us already are; to say it's okay for government to cheat, steal, kill, and threaten is to admit cheating, stealing, killing and threats as moral practices.
Which we, I hope, generally agree to be false.
Actually, no, it will never work that way. The reason is that even though you, and many others, replace 'aggression at the center of society with non-aggression', there will always be the 1/2 percent of humanity who is mentally ill and violent, who is psychotic, or who is sociopathic and inclined to hurt others, and many other cases, which although rare as a percentage, in a city of 50,000 or 100,000 will together create the need for a police force to keep order. There is nothing wrong with this, and there is everything right with it, and this can't be talked away with statements like...
authority is on the exact opposite side of the spectrum; authority is always backed with violence, and those who seek peace in this world will never find it through the libertarian polar opposite, authoritarianism, e.g. the state.The primary argument in this discussion is whether the greatest good would be for the state to be the sole force of control toward the elements of violence and lawlessness, or whether in some fraction this duty should be shared by the people, which implies their owning firearms. I am certain there is a happy medium.