If only you had come here sooner ... we could have helped. I am sorry to say you got royally hosed, that AR is a bunch of junk ... might as well get rid of it as soon as you can.
As a fellow AR'er I will reluctantly take it off your hands. What can I say, I'm just a sucker to help out folks when I can.
Relax, enjoy your new to you AR, and shoot the snot out of it!