ecm is the method, but that is a tool. more specifically, it's a jig. the .stls for the ecm setup are easily enough found.    .22lr is the last remaining mass commercially produced rimfire ammunition. the case has a small amount of priming compound poured into it, and is then centrifuged. this spins the compound out into the rim where it dries. when fired, the firing pin crushes the rim, detonating the priming compound, which lights the powder.
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