The Sauer 404 Magnum Left-Handed Bolt Head is a factory-original replacement component engineered to manage the primary modular locking interface of your switch-caliber left-handed rifle system. Machined from premium, high-tensile tool steel and treated with a highly slick nitrided coating, this "Magnum" (MA) group bolt head is meticulously crafted to fit larger-rim belted and non-belted magnum cartridges including the 7mm Rem Mag, .300 Win Mag, and .338 Win Mag. Built for the S404's lightning-fast take-down design, it decouples from a left-handed 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.