The Sig Sauer Cal-X Kit P320-M18 9mm Carry is a complete conversion system that transforms a manual-safety P320 into the civilian counterpart of the U.S. Marine Corps M18—one of the most proven sidearms in military service. Built on decades of Sig's engineering reputation, this kit gives you the same core design trusted by military professionals, repackaged for the civilian carry shooter who wants proven reliability, modern ergonomics, and optic-ready capability. If you're already running a P320 and want to add a dedicated carry gun or upgrade your platform, this kit delivers military-grade performance in a compact, 3.9-inch package.

What makes the M18 platform stand out is its balance of size and shootability. The carry-length grip keeps the gun manageable for belt carry without sacrificing the hand control you get from a full-size trigger guard. The 3.9-inch barrel and recoil spring assembly are tuned for 9mm performance, and the coyote-tan PVD-coated slide and grip modules aren't just tactical aesthetics—they're durable, corrosion-resistant finishes that hold up to hard use. The included SIGLITE night sights mean you're ready for low-light scenarios right out of the box, and the removable night sight rear plate keeps your options open if you want to swap them later.

The optic-ready slide accepts ROMEO-M17 red dots and any standard SIG-LOC footprint optic, letting you add a reflex sight without gunsmithing. The M1913 accessory rail handles lights and lasers. You get three 10-round magazines in aluminum construction and a manual safety—the same control layout as the military issue. This is a complete kit designed to run, not a parts bin special.

The Sig Sauer Cal-X Kit P320-M18 9mm Carry is a complete conversion system that transforms a manual-safety P320 into the civilian counterpart of the U.S. Marine Corps M18—one of the most proven sidearms in military service. Built on decades of Sig's engineering reputation, this kit gives you the same core design trusted by military professionals, repackaged for the civilian carry shooter who wants proven reliability, modern ergonomics, and optic-ready capability. If you're already running a P320 and want to add a dedicated carry gun or upgrade your platform, this kit delivers military-grade performance in a compact, 3.9-inch package.

What makes the M18 platform stand out is its balance of size and shootability. The carry-length grip keeps the gun manageable for belt carry without sacrificing the hand control you get from a full-size trigger guard. The 3.9-inch barrel and recoil spring assembly are tuned for 9mm performance, and the coyote-tan PVD-coated slide and grip modules aren't just tactical aesthetics—they're durable, corrosion-resistant finishes that hold up to hard use. The included SIGLITE night sights mean you're ready for low-light scenarios right out of the box, and the removable night sight rear plate keeps your options open if you want to swap them later.

The optic-ready slide accepts ROMEO-M17 red dots and any standard SIG-LOC footprint optic, letting you add a reflex sight without gunsmithing. The M1913 accessory rail handles lights and lasers. You get three 10-round magazines in aluminum construction and a manual safety—the same control layout as the military issue. This is a complete kit designed to run, not a parts bin special.