This board is a good place to learn about your rifle. There's (more often than not) a lot of GOOD info to be found here from some very patient and reliable sources. There are a couple of guys here that I really respect and they all have one thing in common: at one time or another they gave high praise to:
The Black Rifle
Author: Blake Stevens (?)
publisher: Military Grade Publications.
cost: $50
They were right. This book is amazing.
It covers the AR-15 from it's humble beginnings through it's painful birth, the hype and the beaurocratic bungling, product improvements, tests, trials, failures, insights and triumphs. Myths are explained, questions are answered and answers are explicit. The more I learn the more questions I have and The Black Rifle is the first place I look. I found the book an invaluable resource for finding those hard to find details, and on top of that- it's very entertaining. If your interest in your AR shows no sign of weakening, you have questions and want the FACTS- you owe it to yourself to get this book! I promise you will pick up this $50 book more often than your $1,000 rifle!