Not a dumb question at all, in fact I was expecting somebody to ask.
The first version of the 45 Colt cartridge featured what was called Benet priming. Named after Col. S.V Benet who was commander of the Frankford Arsenal in the late 1860s. Benet priming was an early form of Centerfire priming. Benet primed cartridges had a folded rim copper case. Priming material was deposited inside the case at the bottom. A piece called the Anvil Plate was crimped inside at the bottom of the case, sandwiching the priming material between the Anvil Plate and the bottom of the case. When a firing pin struck the bottom of the case the priming compound was ignited by being squeezed between the bottom of the case and the Anvil Plate. This photo demonstrates the principle. The Anvil Plate had two flash holes that communicated the flash from the priming to the main charge of Black Powder, igniting the powder.
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In this photo I have pulled out a few of the rounds to compare them to a modern 45 Colt. Yes, from the bottom they looked like a Rimfire, but they were not, they were Centerfire. Notice the telltale crimps at the bottom of the cases holding the Anvil Plate in position. You might also notice these were the 30 grain loads. The original 45 Colt cartridge is often described as containing 40 grains of Black Powder. In fact, even the old Balloon Head cases probably did not hold 40 grains, probably something more like 38 grains or so. The Benet Primed rounds had more interior capacity even than Balloon head rounds, so they were probably the only rounds that could actually hold 40 grains of powder. The 40 grain military loads recoiled too much in a revolver, so the government dialed back the military charge to 30 grains. There is probably cardboard wadding inside to take up the empty space, because Black Powder rounds must not contain any air space. No, I have not dissected any of these rounds to make sure. I want to keep the box complete.
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Here is a photo of 45 Colt and 45 Schofield cartridges. The two cartridges in the center are Benet primed, the two on the outside are my modern reloads.
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The early 45-70 cartridges were also Benet primed. The one on the left is a Benet primed 45-70. These were problematic in the Trapdoor rifles of the time, the extractor could rip through the soft copper rim, leaving the round jammed in the chamber.
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Benet primed rounds could not be reloaded, they were like Rimfire rounds in that they could only be loaded and fired once. When modern Boxer priming appeared, Benet primed rounds quickly became obsolete. The brass Boxer primed 45-70 rounds were not as soft as the copper Benet rounds, so the problem of ripping through a rim with a Trapdoor went away.
While I'm on the subject, here is a comparison photo of a couple of cartridge cases I cut in half. On the left is a 45 Colt Balloon Head round, on the right is a modern 45 Colt Solid Head round. The difference in powder capacity is obvious. I have a box of empty 45 Colt Balloon Head cases, and one of these days I intend to load up some with Black Powder to see how much they will actually hold. In the meantime, my standard Black Powder load for 45 Colt in modern cases is about 35 grains of FFg under a 250 grain bullet. I could stuff more in, but I would be compressing the dickens out of it. There really is no need for more than 35 grains of FFg in a 45 Colt. It is a pretty stout load.
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