Today we're looking at a new book by Maxim Popenker and Anthony G. Williams, Sub-Machine Gun. It should come as no surprise that a collaboration between these two folks results in an excellent reference book (we previously reviewed their work on WWI aircraft guns). This book includes both a detailed section on submachine gun cartridges, and the guns themselves - organized by nationality and focusing largely on experimental and developmental models. It's an excellent reference work, and a valuable addition to a good gun library. You can pick up a copy now while it's still discounted on Amazon: http://www.amazon.com/gp/product/1847972934/ref=as_li_ss_tl?ie=UTF8&tag=forgoweapo-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1847972934