What books to educate me on how and why of component choice

Somebody on these boards has a tag line that says: "Go with a proven performer" Best advice you could get.

Welcome to the world of gun marketing. It's all milspec, it's all HP tested, shot peened, and anyone who says the poverty pony isn't jUsT aS gUd is a shill who's butthurt over paying too much for their x, y, z.

There really is no way to know. All the manufacturers, as said, are going to claim full milspec on everything, and they're all lying and all telling the truth at the same time, at least as far as the truth can be told.

The short answer is buy a Colt BCG and barrel with the correct markings, and pretty much everything else you can buy from any reputable manufacturer. I'm very partial to Aero for receivers. Magpul has A5 extensions now. Get you some Springco goodness to throw in there and you're gtg.

Basically what you're looking for is the combined MP mark on the barrel, and then on the BCG a C stamped on the carrier and again on the underside of the extractor. I've also seen dot matrix marks, and as far as I know those are fine, too.

The next step up from that would be like a Criterion barrel and an LMT enhanced BCG. That's probably like 7/10ths of a KAC at about half the cost.

Something to think about though... A good barrel is going to be around 350, and the BCGs are in the 180-220 range, or were. So even if you get everything else on sale or whatever, you're still probably going to be in it for more than a factory Colt. What I've had very good luck doing in the past is buying factory 6920s and replacing the parts I didn't want and selling them on GB. People pay outlandish prices for Colt take off parts if they're new. About the only thing I replace though is the trigger, and for that I use the Geisselle Super Dynamic Combat.

Thanks a great deal for all the replies and great experience based advice.
My desire for a book or preferably several books is based on how I have learned to teach myself 90% of what I know about guns, and all things mechanical and electrical especially as it pertains to how I earn my living that began as a heavy industrial maintenance electrician but in the last 10 years morphed into a hybrid electro-mechanical technician
I am an emergency electrician that is directly responsible for getting multimillion dollar equipment back up and running ASAP for every minute this equipment is down the loss in profits are so great they are measured per minute and vary from $2-$3k per minute to over $60k per minute
Most of the electrical and all the mechanical systems, individual components and equipment I am responsible for I have received either the most minimal of training on or no training at all so I am forced to get a maintenance manual and teach myself how the system works and how to fix it.
I bought my first AR-15 close to 7 years ago. Knew before that very little other than the AR-15's history and development by Eugene Stoner, James Sullivan and Robert Freemont.

Once I began trying best educate myself on the use care and maintenance of my AR-15, I immediately discovered there were and are still to this day HUGE amounts of misconceptions, false information and even outright BS surrounding the AR-15 rife during its earliest performance during it's first days of service in Vietnam in use especially by our regular infantry forces.
I have owned and shot firearms since I was 12. Began my life with guns at age six with of all things a Daisey Red Rider BB gun no less. My friend introduced me to the AR platform 8 years ago and I instantly fell heads of heals for it.
I now own a BUNCH. So great is my love for the AR-15 I feel owning one is THE definition of what it is to be a free person and an law abiding American.

As has been said everyone selling ALL THINGS AR-15's from parts to complete rifles all claim their parts are Mil-Spec, shot peened, MPI HP etc etc and we consumers have NFI and NFW to determine if it's their truth or not.
So we are left with the best option of buying strictly from well known long established companies and hope for the best.

The market, companies, and new products change way too fast to rely on anything that wasn't printed yesterday, and even then, it's only good for about a month.
Frankly, the things you're going to hear about on the internet are those things in common supply/use, and individual examples of failure.

This forum has collected information in real time on most things that have been released, and peer reviewed to at least some degree. This is more than any book on the subject that I am aware of.
There are a few facebook groups that do a pretty good job of collecting information, but the nature of social media has made most of the discussions nearly worthless past the first post and a few comments. Combined with the anti-firearm bent of those platforms we are also being slowly drowned out of those spaces, which SHOULD BE a sign to those participating in technical discussions that they are going to need to return to the forums that have been being choked out by the ease of popular social media.

We have been part of this specific community for a long time specifically to help folks like you looking for that information.
THIS THREAD IS NOT THE PLACE TO PROVIDE THAT INPUT.
Do some searches, read some threads, ask some questions after your research.
In the end, there are many vetted suitable items on the market to meet ANY need you may have for an AR, and if not, it's probably because it's a bad idea.