Post 11/4, AR lower receivers have become difficult to find. I thought I'd mention you can call
www.Aimsurplus.com and get on a waiting list/notification list. Also,
www.essentialarms.com is taking orders and is currently shipping within 2 weeks of orders. The EA website is outdated - lowers are now $100 for a basic anodized model w/ no quantity discounts and a maximum of 3 lowers per person per week.
www.ar15.com has a great build it yourself forum. Here is the main thread on assembly:
http://www.ar15.com/forums/topic.html?b=3&f=4&t=226782www.Brownells.com has a variety of FREE videos for download on their website about building an AR-15:
http://www.brownells.com/aspx/NS/GunTech/newsletterarchive.aspx?x=vFor those new to building ARs, the only part you need an FFL for is the lower receiver. Everything else can be shipped to your doorstep: triggers, stocks, bolts, sights, barrels, upper receivers, etc.
Most AR lowers are pretty much the same and are built to mil-spec dimensions. The only brand to keep away from is Vulcan/Hesse, as these are cast, not forged.
Some quality brands of lowers include: Essential Arms, Spikes, Anvil, Stag, DPMS, Colt, Armalite, Bushmaster, LMT, LaRue, Noveske, Aero, Mega, Superior, Sabre, Rock River, CMMG, and Doublestar.
A lower receiver requires a minimal amount of tools to assemble: hammer, punches, vise grips, screwdrivers. Adding a barrel to an upper receiver can require a barrel wrench and action block.
ARs come in a variety of calibers for various purposes:
-Plinking (.22LR, 9mm, .223 Rem)
-Home/self-defense (9mm, .223 Rem, 6.8SPC)
-Hunting (.223 Rem, 6.5 Grendel, 6.8 SPC, .458 SOCOM, .450 Bushmaster, .50 Beowulf)
-Target shooting (.223 Rem, 6.5 Grendel)