There is a 12th edition which, in my opinion, is outdated and in need of revision (13th edition). Unfortunately, Dr. Ezell is deceased. The first chapter of the 12th edition has been expanded to include a wider array of firearms, including an indepth discussion on the HK's G11 and its ammunition.
The second chapter on machine guns has similarly been expanded. There's more info on the XM248, FN's Minimi and even the XM106 (M16 based SAW).
The third chapter on SMGs includes a lenghty discussion on caseless SMG ammo and drawings of the Fiocchi-Benelli SMG.
The fourth has info on Blank Firing Attachments, grenade launchers and newer shotguns.
In the Sporting Guns section the two Mini14s shown (GB & GB with folding stock) have been mislabeled as full automatic. The section itself has been expanded to include a lot of semi-automatic weapons (at one time freely) available on the U.S. market (Austrialian Leader, Valmet M71S, Egyptian Maadi).
The 12th edition (as well as the 10th) is well worth addition to your shelf.