Terry, I'm in the unusual position of being delighted to tell you that you are wrong.
At least as i understand it. I looked at the UN treaty, poured over every word of it, and the issues surrounding it very carefully. There are several things wrong with the word on the street about the treaty:
1) It really does have zero affect on the internal affairs of the US and how it handles gun ownership. Current US law (FFL, NFA, background checks, etc.) already MORE than fulfill the small section of the treaty that has to do with internal regulation of firearms sales and ownership. It really is only about exports and accountability for selling arms and hardware to governments and regimes that use them to oppress their people.
2) UN treaties cannot supersede US law. We would have to repeal or redefine US law via due process in order to comply with a treaty that did conflict with US law.
3) Ahem. The US never ratified the treaty that declared that signed treaties are enforceable until brought to the floor for ratification. Oh, the irony.
The actual danger of the treaty is that it is likely to inspire a national conversation about gun control at the federal level. While the treaty itself doesn't mandate that the US do anything differently any conversation about gun control is an opportunity to pass new legislation about it. Including, in my mind, legislation that is PRO GUN. Pro gun activists may be missing an opportunity in politicizing this treaty so fiercely - and as far as I can tell, wrongly.
I don't trust the UN. I don't trust the US government, either. Both need to be watched and controlled - as do all governments. But this treaty is not, as far as I can tell, the gun banning backdoor to bypassing congress horror that it has been made out to be.