all I have to say is, he is asking questions of a total newb to shooting and rifles, but the guy is in the process of building an AR and has it almost complete, yet just read about headspace, least we can do his help him keep from blowing his fool head off. we were all there once, did we attempt to build a rifle before we knew what headspace was? give the man credit, he wants to learn!
RR

I did have a scope cap stick one time, and when I tried to take it off to adjust the scope the whole piece screwed out of the scope. So I know it can happen. I had to hold it with pliers to get the scope cap off. It was an old tasco that came on a used gun I got, I guess whoever put the cap on previously tightened that sucker down as tight as they could! I couldn't believe you could tighten a cap down tight enough to do that.

I used to go into armories and ask these kinds of questions... Now I just make different forum accounts....