Halie Kitchell, Tori Burke, Brooke Roberts, and Alaina Smith
Interchangable Parts and the Industrial Revolution.
Since machines were becoming a big part of all manuifacturing, and was pretty much taking over the manufacturing in the U.S. Which helped tremendously with jobs and the economy. People who weren't as smart or skilled as some were able to have jobs working for the firearm industry.
This is a picture of Interchangable parts in the firearm industry.