Rimless cartridges are a type of ammunition designed without a protruding rim at the base. This design allows for a more streamlined shape, making them easier to feed into firearms, especially in semi-automatic and automatic weapons. The absence of a rim also helps reduce the overall weight of the cartridge, which can be beneficial for both the shooter and the firearm. These cartridges are often used in modern firearms, such as pistols and rifles, where reliability and efficiency are crucial. Popular examples include the 9mm Luger and the 5.56x45mm NATO. Rimless cartridges typically rely on the case's extraction groove for ejection, ensuring smooth operation during firing.