Characteristics
Rimfire cartridges are limited to low pressure calibers because they require a thin case so that the firing pin can crush the rim and ignite the primer. Although rimfire calibers up to .44 (11 mm) were once common, modern rimfires tend to be of caliber .22 (5.5 mm) or smaller. The low pressures mean that rimfire firearms can be very light and inexpensive, which has helped lead to the continuing popularity of small-caliber Rimfire Cartridges.
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