I suspect that cartridge sectioning began right after the first metallic cartridge was made, maybe even paper ones, just to check that the rounds were made correctly. My involvement began when I was collecting .30-06 and Chris Punnett was sectioning them. Chris’ work is superb, as anyone who has read his .30-06 book will confirm, and Chris would sometimes section a few extra rounds and offer them to collectors. He did some very nice rounds for me.
When I was working on my Gyrojet book, I asked Paul Smith to do a few rockets. Then a few more, and now I just counted 57 of Paul’s masterpieces in the book. Here’s one of my many favorites:
This sectioned MBA 5.56mm “Ammunition Concealment Round” is a great example of the value of a well-sectioned cartridge. For the first time, I was able to see exactly how it was put together by MBA. I had no factory drawings of the round but, as I’m sure Paul will confirm, actual specimens sometimes do not match their “official” drawings and the only way to know for sure is to section one to see, even if you do have the factory drawing. I had all the components of the round but was not 100% sure how they went together. Sometimes I was very surprised at what a section showed, as with the MBA .45 caliber Gyrojet that turned out to have very thick case walls, a normal-looking nozzle with a normal-looking primer that appreas to be live, but no propellant in the case. You just never know what you’ll learn, and Paul’s work added a great deal of information to the book. Plus, they look really neat.