So most of my firearms experience has been dominated by handguns, and even then I'm by no means an expert. Rifles are a relatively unexplored avenue for me.
I've searched about here and found the general consensus that Colt LE6920 is about the bottom of where one should look in regards to a reliable, entry-level rifle. I do recall at one point Chuck Haggard was testing out the M&P Sport line and reported favorably, so they may be an option as well. Overall though, aside from some basic knowledge of the inner workings of the AR platform, I'm not terribly up to speed on the minutiae of overall parts quality and what I should really be looking for or checking against when I purchase a rifle or eventually get in to building one.
The internet has proved to be a tad overwhelming at points and as such I feel the collective here could provide better guidance than stumbling around random websites trying to understand what makes a good bolt carrier group or what it means that some rifles may be over-gassed.
Any particular books or sources I should consider in my journey towards a better understanding of rifles and their parts quality?