I am one of those guys who didn't know one end of an AR 15 from a hole in the ground until just the last few weeks. Have to confess to being more a fan of the larger calibers, and also spending much more time shooting .45 acp pistols.
However, I caught your post two nights ago, and came home from work last night and followed those additional links you added. Thanks again. But...
I'd like to ask you if you know of a book equivalent of "AR 15's for Dummies." For instance, I know now about the whole Lowers and Uppers deal, and how the Lower is FFL-necessary component, and since following your links I also know a little about loading .223 for both bolt actions and AR platforms. Man, I have to admit that I've been overlooking what appear to be really cool rifles. Now I'm stuck trying to play catch-up, with the dark cloud of the political scene moving overhead like an incoming storm. Meaning, that I've gotta educate myself fast, and try to get my mitts on what gear I think will be most important.
I asked about the book idea because I still am hazy on things like the "tube" which is noted for when you want to outfit your rifle with a collapsible stock, for instance. From what I've read online, the designation of your rifle as a carbine, or something else, is going to determine what you need if you want to set yourself up with a collapsible stock. This is one of the first questions that comes to mind for me, but I'm sure others will surface.
Again, I would like to thank you for taking the time to post the info which you've put up there already. I'm calling my favorite shop tomorrow and make arrangements for the Stag lower unit. Now I need to figure out what the heck to do in constructing an upper. I've had my mind opened up - bigtime - to this whole AR world. Trying to make up now for lost time, and trying to do this in a hurry too.

Your knowledge in this area has been the opening of the AR door for me, maybe for others of us out there too. - DixieBoy