Book Review: Firearm Anatomy I – Thompson M1A1 Submachine Gun

Firearm Anatomy I: The Thompson M1A1 Submachine GunOne of the questions I have gotten quite a few times is what resource I would recommend for folks who are interested in the technical engineering aspects of firearms design. It’s always been a tough question, because apart from Chinn’s multi-volume work (which is crazy expensive to buy in print now, although it is available online) there are very few book that I’m aware of. Until now! I just got a copy of David S. Findlay’s new book on the Thompson M1A1, and it is exactly the work that an aspiring firearms designer should get a copy of.

The title doesn’t really convey the scope  of the book – it is not about the history of the Thompson, or the development of its different variations. Instead, Findlay (who is a second-generation firearms engineer with 7 patents to his name) takes the M1A1 and provides a rigorous and detailed analysis of its mechanism. The M1A1 was the final simplified version of the Thompson, which abandoned the Blish system and worked on a plain blowback concept. Findlay’s analysis looks at the elements of bolt weight, spring force, friction, gravity, propellant gas movement, buffer elasticity, and other factors in determining rate of fire of the gun. There is as much math as text in the book, as all of the calculations to understand these factors are drawn out in detail. In addition, the calculations to determine the characteristics of oval magazine springs are also included in their own dedicated chapter.

The book is 340 pages in total, and the mathematical analysis of the gun only takes up the first 75 or so. The remainder of the volume consists of a complete set of reverse-engineered technical drawings for every part of the M1A1, right down to the pins. These drawings are further broken down into discrete machining step. The barrel, for example, is covered by 9 separate drawings for the initial cutoff, drill & ream, rifling, hub turning, hub threading, contouring, chambering, finishing radii, and final finishing. The upper receiver has 38 individual drawings, starting from a single billet of material. These are not blurred and fuzzy copies of original blueprints, but fully dimensioned computer-printed drawings reverse-engineered from an M1A1 by a professional firearms engineer.

In short, if you want to know how to build a Thompson, with the supporting knowledge and understanding to design and build a blowback firearm of your own design, this is exactly the book you have been looking for. It is so significantly distinct from material like P.A. Luty’s that I am hesitant to even bring up the comparison, as Findlay’s work is at a whole different level. As he discussed in the preface, Findlay wrote the book to stimulate and support interest in firearms design – historically speaking, we are due for another major breakthrough in firearms technology and this book is for the people who will go on to make the next innovation.

I should point out that you know a book will be good when it had to be approved by the State Department for International Traffic in Arms Regulations compliance prior to publication… 🙂

So, if you are one of the people who has asked me where to find a book like this, get thee to Amazon and pick up a copy! It’s the best firearms engineering book I have seen, if not the only one (other than Chinn’s) and the more technically disposed you are, the more you will appreciate and learn from it.