Damn... I missed that SWAT special. How about a .pdf copy for the rest of us, Yard Dog?
WRT the Duncan Long series, I have three in the AR series, copyright dates 1985, 89, and 92. Prior to Arfcom and widespread use of the Internet, these books were the greatest. I must have read through each one several times. By today's standards, they leave much to be desired, but in their day it was fantastic to have books devoted to the subject. The earliest book,
The AR-15/M-16; A Practical Guide was illustrated mostly with inaccurate line drawings. Artwork notwithstanding, the books all offer a wealth of information, and will become classics.
Before that, my best source of info was the 10th edition of
Small Arms of the World, 1973. This was way before the AW craze hit. I remember seeing a Colt AR-15 in a gun shop in those days for $200. WAAY too rich for my blood at the time!
The first time I became aware that there was a new trend emerging was when I got the July '81 issue of
Guns & Ammo. They ran a long feature article entitled, "Tomorrow's State-of-the-Art Sporting Rifle." Shortly afterward, they came out with their special issue "Assault Rifles," which seemed to be an in-depth expansion on the original magazine article. This was followed by a whole slew of special issues from all publishers. I doubt that I have them all, but I did my best!
But back to the present... one of my favorite books is the one by Scott Duff, entitled
The AR-15 Complete Owner's Guide. I have the first one, but I believe there's a part 2 available, as well. IIRC, Fulton Armory has them. Somebody correct me if I'm wrong. The current AR specials by G&A are good additions to the library, as well.
Buy all the books you can now, including military manuals. You just never know when these sources are going to dry up.