One of the unsung inventions of the industrial revolution was the go / no go gauge. Most mechanical parts have only a few critical dimensions, and the go / no go gauge was used to make sure the part fit, in the most literal sense.
Before the industrial revolution, the artisanal apprenticeship system placed heavy value on training a single person to perform all aspects of a particular manufacturing operation. Gunmaking apprentices were taught to carve the wood stock; forge and file the lock work; and to weld, turn and rifle the barrel. Apprenticeships typically lasted years before the apprentice became a master of his trade.
The older artisanal system of production gave craftsman the flexibility to make each workpiece with individuality, since the same craftsman would be hand-fitting each part together. Since no two guns were completely alike, parts could not be interchanged.
The advent of mass-production meant that parts needed to be made to a common standard, such that the need to fit parts would be minimized. One of the easiest ways to ensure that a part’s critical dimension were correct was the pass / no pass gauge.
The go / no go gauge pictured here is one such gauge. It was made by an unnamed machinist at Smith & Wesson to gauge the back of the barrel on the “.38 CAL 1876,” otherwise known as the “Baby Russian.” Perhaps its most notable feature are the bright wear marks in the middle of the tool. These almost certainly came from repeated handling and use.
The astute eye will note that the “S&W .38 CAL.” lettering is in a different font. It was almost certainly added later—a necessity when the tool room filled up with similar tools for other guns.
Tools were typically made by the machinists that use them. In fact, making tools was often how a machinist learned the trade. His tools became part of his magnum opus; a more intimate expression of his craft than the guns that came across his workbench. The guns were the work of many craftsmen, but the tools remained uniquely his.
Lest I be called out for sexist language … the use of the engendered pronoun “his” is deliberate. This was a time when a machine shop and the vocation of machining was the dominion of men. This would change decades later, of course … most notably during World War 2, when women played a huge role in America’s military industrial complex. And women did indeed work in the gun shops of this era—typically doing the fine work of assembling ammunition.