3. Achieving Interchangeable Gun Parts (Part 1) – Eric Johnson Explains Posted on October 18, 2021 by Admin words https://web.archive.org/web/20121020155133/https://civilwarscholars.com/2011/09/the-man-who-changed-the-world-that-you-never-heard-of-eric-johnson-explains/ VIDEO: Achieving Interchangeable Gun Parts – Eric Johnson Explains – TRT: 7:58 Gunsmith Eric Johnson