During World War I, the national arsenals kept manufacturing the M1903 rifle, while industry was asked to manufacture the M1917. The arsenals decided to document their manufacturing processes anyway, just in case… and the process was published in a book, postwar, by Fred Colvin and Ethan Viall.
While the title of the book is United States Rifles and Machine Guns, it’s almost entirely about the manufacture of the 1903 — part by part and process by process. One gets the impression that the arsenals didn’t actually have a really systematic set of process sheets before someone asked them to make them up for war production; that before that request, this was all tribal knowledge contained in the foreheads of foremen and minds of machinists.
The sheer complication of 1903 production is one take-away from this book, but another thing that really struck us was that this 20th Century rifle, an icon of mass production, was not entirely produced by machines. Along with many machine setups and many trick jigs and fixtures, there are significant hand operations. Here’s one example. If you have a Springfield (or a Mauser, close enough), pull out the bolt and look at its face. See how the bolt face is relieved or “counterbored,” so that the head of the cartridge case is supported? This Is the two-step operation that produces that counterbore. And while the rough operation is done with a powered drill, the finish operation is done with a hand tool. First, let’s look at the rough cut:
OPERATIONS 45 AND 45½, COUNTERBORING FOR HEAD SPACE, ROUGH AND FINISH
Transformation: Fig. 725.
Machine Used: Pratt & Whitney 14-in. upright three-spindle drilling machine.
Work-Holding Devices: Drill Jig, Fig. 726; bolt handle stops against a stop, while clamps are drawn down on body by an equalizer bar.
The bolt is on the left, the jig on the right. We’ve omitted Figure 727, which is a scaled three-view providing more detail the drill jig in Figure 726 and the way it locks in the bolt. It’s obvious that getting this right (or wrong) has serious implications for headspace, which affects safety and accuracy.
The hand operation’s setup is shown below. It too requires a specific jig. Since here we’re in the forty-something’th operation on the bolt alone, and almost every operation needs one or more jigs or fixtures, the tooling requirement for an early-20th-Century rifle plant is mind-boggling.
Why the hand operation? Our best guess (because the book doesn’t say why) is that, while the Pratt drill press was great at removing a lot of metal, it didn’t have the precision needed (“safety and accuracy,” right?), so a finer cutter in a hand fixture finishes the cut to exact depth and desired surface finish.
As Europe slid into war again, the arsenals were making a new rifle, the US Rifle M1. One suspects this book was the guide for industry as they, once again, produced a version of the 1903, this time with countless manufacturing simplifications. Many manufacturing processes were simplified (and more hand operations eliminated) as the war replaced and supplemented prewar craftsmen with wartime hires longer on enthusiasm than experience.
Incidentally, for the set-up seen here, the book even shows how the cutters and pilots are made, and their dimensions. (There are separate rough and finish cutters). It doesn’t show all the gages that must have been used by both the set-up men and operators of the machinery, let alone the inspectors.
It does show enough that you could probably set up your own Springfield factory and do it exactly the way they did it back in 1917 — if you could find a supply of 1917 Connecticut River Valley gun-industry craftsmen to make all these cuts for you. And if you could get some billionaire to fund you. (Well, there are two famous billionaires competing for the same job right now, one or the other will be looking for opportunities in a couple of weeks). Good luck!