This measurement refers to the width of the base of a specific cartridge where it meets the chamber of a firearm. It is a critical dimension for ensuring proper chambering, extraction, and overall function in firearms designed for this ammunition. For instance, a cartridge with an incorrect base dimension could lead to malfunctions ranging from misfires to catastrophic failures.
Accurate and consistent base dimensions are crucial for safe and reliable firearm operation. This specific measurement is vital for manufacturers to ensure interchangeability and proper functioning across different firearms chambered for this popular round. Historically, standardization of such dimensions has been essential for military logistics and interoperability, and remains a key factor for civilian shooters as well. Variations, even minor ones, can affect pressure levels, accuracy, and the firearm’s longevity.