I have assembled a few lowers and the first time I had some issues but it's really not that complicated. The hardest part was getting the front pivot pin detent in without shooting it across the room.

You need some punches and some pliers. No drilling.

This should help.

http://www.ar15.com/forums/topic.html?b=3&f=4&t=226782

Edit: Perfect post # for AR-15 topic. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />