I've spent the past couple weeks with the later (late 80's) edition, and I think it's a pretty good book. The best part of reading older books is to realize how old some of the arguments we're having today are... I'm seeing texts from the 70's and 80's talking about how SMGs are completely obsolete in the face of intermediate-caliber SBRs. And, yet, here we are 30 years later, still trying to decide whether they're obsolete. *facepalm*Small Arms of the World
I have two copies: the 1960s edition shown in this video, and a more recent edition.
The first 1/3 is a detailed overview of small arms development. The second 2/3 is a breakdown by nations, showing their military arms. There is not just identification, but operating and disassembly instructions.