Sig Sauer 320 Frame Fire Control Unit Custom Gld

The Sig Sauer P320 Fire Control Unit (FCU) is the serialized heart of your custom P320 build. This complete fire control unit drops into any compatible P320 grip module, giving you the foundation to assemble a pistol tailored to your preferences and shooting style. Whether you're building a competition gun, a duty-ready carry piece, or a range toy, the P320 FCU is the platform that makes modular P320 customization possible.

Sig engineered this FCU with a titanium nitride finish on both the frame and skeletonized trigger, combining durability with a clean, purposeful aesthetic. The titanium nitride treatment resists corrosion and wear—practical upgrades for a part that defines reliability in your build. The skeletonized trigger reduces weight and snags without compromising function, appealing to shooters who value precision and ergonomic refinement.

This fire control unit is compatible with all P320 grip modules chambered in 9mm, .357 Sig, or .40 S&W, and works with all post-upgrade P320 accessories. That compatibility opens up real flexibility: pair it with the grip, slide, and barrel that fit your mission, swap uppers for different uses, or experiment with sight and control configurations. It's the modular approach that made the P320 a favorite among serious shooters and professionals.

If you're already deep in P320 customization or planning your first build, this FCU gives you a proven, precision-made base to work from.

Key Features

• Titanium nitride frame and skeletonized trigger for corrosion resistance and lightweight performance
• Drop-in design compatible with any P320 grip module
• Works with 9mm, .357 Sig, and .40 S&W P320 configurations
• Compatible with all post-upgrade P320 accessories for endless customization
• Complete fire control unit—everything needed to build or rebuild a P320

Specifications

Frequently Asked Questions

What grip modules is this P320 FCU compatible with?

This fire control unit works with all P320 grip modules. You can pair it with small, medium, large, X-Series, or any other P320 grip frame to customize your build for your hand size and shooting preferences.

What calibers can I build with this fire control unit?

This FCU is compatible with P320 uppers and barrels in 9mm, .357 Sig, and .40 S&W. You can swap uppers to change calibers while keeping the same fire control unit and grip.

Do I need anything else to complete a P320 build?

The FCU is the core component, but a complete P320 also requires a grip module, slide assembly (or separate slide and barrel), and any desired accessories. This FCU provides the serialized fire control component; other parts are sourced separately based on your build configuration.

Is the titanium nitride finish worth the upgrade?

Titanium nitride improves corrosion resistance and wear resistance compared to standard finishes, which is practical for a part you'll rely on long-term—especially in carry or duty use. It's also a refined aesthetic that appeals to builders focused on quality.