Dated now, since it was published in 1981, otherwise I'd give it five stars, but still outstanding as a clear explanation of, as the title says, how weapons work. A necessary adjunct for anyone who studies military history - you can't study a profession without understanding its tools, which both shape and are shaped by strategy and tactics. Full of extremely well-done illustrations. Not only for anyone interested in military history, but for a reader intrigued by technology in general, this is worth picking up, even though it's outdated and out of print.