Flounder, you have greater trust in elected officials than do I. Would you ever have believed there would be a law that required you to buy health insurance or suffer penalties and the possibility of seizure of your money or property by a new army of IRS agents expressly hired and trained for that function?
I have no faith that someone like Obama and his cohorts would not use the treaty to accomplish controls they can't arrive at any other way.
Remember, a ratified treaty essentially becomes law in the U.S., requiring/allowing administrative systems to enforce it. So consider some of the proposed treaty language that would require signers to prohibit/control sale of "small arms" that might....
" - Be diverted to unauthorized end-users for use in a manner inconsistent withthe principles, goals and objectives of the Treaty, taking into account the risk of corruption.
- Be used in the commission of transnational organized crime as defined in the United Nations Convention against Transnational Organized Crime.
- Be used to support, encourage or perpetrate terrorist acts."
Now, do you think it at least possible that someone of Eric Holder's ilk might interpret that the sale of a .45 ACP in your local gun shop "might" lead to any one or all of the acts described above - and therefore must be controlled by the Federal government so as to be in compliance with the treaty?
When a camel sticks its nose under the tent the best thing to do is kick the nose as hard as you can.
E-mail your Senator, dammit! 
By the way, "transnational organized crime = Mexican/American drug cartels.