Sig Sauer, P320 Custom Works Fire Control Unit, 9mm/.40/.357, Gold Nitride

The Sig Sauer 8900160 P320 Custom Works Fire Control Unit is a gunsmith-grade upgrade that brings the proven modularity of the P320 series into a premium component for builders, armorers, and service professionals, and because this is the serialized FCU it is an FFL item that must be transferred through an FFL; this Gold Nitride unit paired with a titanium frame and flat face skeletonized trigger delivers a crisp, consistent break and corrosion-resistant finish that benefits competition shooters, duty carry personnel, and custom build enthusiasts who want a refined trigger feel and durable wear surface. The P320 platform was designed from the ground up to accept different grip modules, slides, barrels, and optics, and this Custom Works FCU drops into existing Sig P320 parts and assemblies, supporting calibers like 9mm Luger, .40 S&W and .357 Sig when combined with the appropriate barrels and magazines; that modular compatibility makes it ideal for armory upgrades, caliber conversions, and tailoring trigger geometry for match or operational demands. With Sig Sauer engineering behind it, this FCU adds premium materials and finish to the semi-auto pistol platform, offering reliability and a high-end tactile experience for those building or upgrading a P320.