A few months back I posted some comments on the manufacturing methods of S&W back in the 1950s by a good friend of over 30 years who is a engineering physicist and works in (as he calls it) the military/industrial complex. I thought he would be interested in these photos so I forwarded the link to this thread. Here is his response, which I share with his permission. I hope you will find his background information on manufacturing of additional interest.
"The S&W factory looked pretty much the same when I visited it in the mid-1970s. Since then it has apparently changed substantially.
You might appreciate a few comments about the manufacturing process. This article shows that S&W is a textbook example of what is now known as the American system of manufacturing. This system uses dedicated, single-purpose tools operated by semi-skilled labor to make high quality, interchangeable parts. Quality is determined by design, careful selection of material, repeatable processes, and continual checking of production against standard gauges. In contrast, the European system (also called the English system) uses general purpose tools operated by skilled craftsmen. There is considerably more variation in quality using the European system, and considerable hand fitting is usually necessary. The initial capital cost to start production is usually lower with the European system, but labor costs are higher. Examples of the two systems are the M-14 and FN FAL rifles. There are fewer, more complex parts in the M-14 than in the FN FAL. Further, a higher level of metallurgy and quality control is required to make the M-14 over the FAL. The FAL was an easier design to make using general purpose tools, and was made literally all over the world. On the other hand, even US manufacturers had trouble making the M-14. The European system may lead to lower manufacturing costs if labor is cheap, as it is in a lot of Third World countries - or China. The European system is also easier to change if the design must be modified.
The S&W revolver frame at the time of the article was made as a closed die forging. This process makes a forging that is close to near net shape, with excellent metallurgical properties. Also shown are a variety of single purpose machine tools used for various operations. One of the most important processes, used to make the rectangular opening in the frame for the cylinder, is broaching. This process is almost unheard of today. When the enormous capital cost of the tooling is considered, it is easy to understand why companies using the American system changed designs with great reluctance. On the other hand, once set up the American system produces a tremendous volume of high quality product.
Today manufacturing is moving back to a modified form of the European system, in that parts are often made on computer controlled machine tools (CNC). Dimensions are spot checked rather than measured against dedicated gauges. General purpose computer controlled machining centers are not as stiff as the single purpose tools shown in the article. The additional flexibility leads to looser manufacturing tolerances (some will argue this, but the statistical studies done by my company are very clear; sometimes the computer controlled machines cannot even get within a factor of two or three of the tolerances produced by single purpose tools). In addition, the lack of stiffness means that keeping up production rates requires softer metals, which cut more rapidly than harder forged metals. So quality today is much more variable than in the past, and durability also suffers since the quality of the metals is lower. Compare your older S&W revolvers with a current production Ruger LCR, for example! In support of this, note that gunsmithing is often necessary today for fitting parts to a 1911 - and this design was originally intended for complete interchangeability of parts by troops in the field."
My friend is a student of history and a military veteran. While in the Army he was assigned to the Test & Evaluation Center at Ft. Benning, GA. Over the years I have never found him to be factually incorrect in anything he's told me.
Dave