Check out
Roderus Custom Gunworks. Frank Roderus has got a few videos where he builds up guns from 0% forgings or 100% frames. I have his AR-15 video where he builds up from a 0% forging and it's pretty good. Gives you an idea of what goes into machining a lower receiver. His first video was on building up custom 1911's from WWII era guns. Frank's a good guy and I've spoken with him personally over the phone. He's also got a forum on his website that's full of info and garage gunsmiths.
There's also the AGI videos, but beyond showing you a little about how the internals function together they can be a complete waste of time if you're actually looking for something more informative.
Someone has already meantioned the Jerry Kuhnhausen books, and I agree. You can get them all, including the new ones at
www.gunbooks.com. Other books worth owning are "Gunsmithing Rifles" by Patrick Sweeney, "Gunsmithing Pistols and Revolvers" by Patrick Sweeney, and "Gunsmithing Shotguns" by Sweeney. "Gunsmithing at Home Lock Stock & Barrel: Lock, Stock & Barrel" is a great overall general book, where the Sweeney books actually get into specific things to do with pistols, rifles and shotguns down the the specific models. And as previously mentioned, the four volumes of the Gunsmith Kinks books from Brownells are full of useful tidbits.
Get yourself a Brownells catalog. More general purpose and special tools than you could ever use. Tell them you are a student/apprentice gunsmith when you order.
www.tanneryshop.com has blueprints for 10/22's, FAL's, AR-15's, 1911's and AK47s. They also sell 0%, 40%, 60% and 80% receivers and other assorted pieces for making guns.
First project: Get yourself a Ruger 10/22 and "Gunsmithing Rifles" by Patrick Sweeney. He's got a chapter on that specific rifle in there. The most relevant and cheapest thing you could do is start changing out the factory internals (hammer, sear, springs, etc.) for models from Power Custom or Volquartsen. You'll need a set of punches, which you can get at Lowes, Home Depot, Brownells, etc for ~$10. You'll probably want a set of files as well, and a good set of gunsmithing screwdrivers or bits which you can get from brownells.
Or, get the Kuhnhausen Mauser book and pick up a C&R Mauser. With the right tools you can do just about anything to one, and messing up won't set you back a lot of money.
Remember the Alamo, and God Bless Texas...