The Sauer 404 Standard/Medium Right-Handed Bolt Head is a factory-original replacement component engineered to manage the primary modular locking interface of your switch-caliber rifle system. Machined from premium, high-tensile tool steel and treated with a highly slick nitrided coating, this "Medium" (ST) group bolt head is meticulously crafted to fit standard-rim cartridges including the .243 Win, 6.5x55 SE, 6.5 Creedmoor, .270 Win, .308 Win, and .30-06 Springfield. Built for the S404's lightning-fast take-down design, it decouples from the main bolt body in seconds without complex tools, allowing a seamless caliber change while maintaining absolute headspace specifications. Featuring a robust six-lug locking design that seats directly into the barrel breech ring for incredible action strength, every individual factory bolt head leaves the J.P. Sauer & Sohn German proof house fully test-fired to guarantee absolute dimensional integrity and unwavering structural safety.