I would like to SLOWLY start purchasing an AR piece by piece. When I mean slowly I'm talking 6-9 months. I'm very new to the whole AR thing and with so many regulations in California it seems almost anything is illegal. So I figure the combination of all the laws along with my inexperience with the AR it would be best to go at this slowly. I leaning toward a 16" barrel chambered in 223 with a quad rail. That's really all I can say I'm for sure about. With the research I have started I've found the AR to be a completely different world with more options than one could imagine. What I'm looking for here are the names of decent manufactures for AR's. I don't want anything close to top of the line, but I don't want a pile of junk either. So what manufactures would best suite me? Rock River, DPMS, S&W, CMMG, STAG, DEL-TON? Also, say I buy this AR piece by piece? How is this gun registered? I was under the impression you can swap out lowers for lowers and uppers for uppers. Are all uppers serial coded so every upper you get is registered? Switching the lower out means nothing as for registration? Also some good AR parts websites would be greatly appreciated. Thanks for the much needed help.