"In any field, certain books are recognized as classics. Serious riflemen/experimenters have for two decades placed "Hatcher's Notebook" in this category ... this extensive work is probably the most useful single volume available to riflemen? -- Game News
Julian Sommerville Hatcher, was a U.S. Army major general, noted firearms expert and author of the early twentieth century. He is credited with several technical books and articles relating to military firearms, ballistics, and autoloading weapons
Just a short review here on a classic reference book. General Hatcher's entire Army career was spent with the Ordnance branch. He was a firearms enthusiast and had a gift for technical matter. He was involved with the development (not the invention - that's different) of most of the small arms used by all of our service members (Navy, Army, Marines, Coast Guard) as well as the training programs from 1912 - 1947. In other words his work had a direct impact on the small arms carried and used in World War I, World War II, Korea and to a lesser extent Vietnam. That's quite a legacy.
In addition to that impressive achievement Hatcher was involved with several tertiary projects such as testing the strength of heat treated steel, what happens when a barrel is obstructed and various types of powder. Though he never saw combat (that I know of) and did not lead troops in combat his contribution is just as impressive from the technical end.
During his lifetime he wrote many books, but "Hatcher's Notebook" is considered to be one of his greatest. In it there is a lifetime of information covering everything from different mechanical principles to research on heat treating, strength testing of various military rifles to barrel obstruction research to ........ well suffice to say there is just a lots of information.
Though definitely a technical book it has a flow and actually is very easy to read. Hatcher was aware that he was writing for firearm enthusiasts who probably did not have his years of experience or a degree in Engineering (U.S. Naval Academy (Annapolis); Class of 1909). It is loaded with photographs and line diagrams that illustrate the various mechanical principles as well as things like recoil compensators and so on. If you are a hardcore, dyed-in-the-wool gun enthusiast then this is the book for you. If you are also a fan of classic firearm literature and enjoy the history of firearms/development.....well you get my point.