FIRE CONTROL UNIT

PRODUCT DETAILS

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SIG SAUER COMPLETE FIRE CONTROL UNIT FOR 9MM/.357 SIG/.40 S&W P320 PISTOLS – 8900160

The Heart of the P320: Elevate, Customize, and Command With the Genuine SIG Sauer FCU

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Introduction: Build the P320 of Your Dreams

The SIG SAUER Complete Fire Control Unit (FCU) for 9mm/.357 SIG/.40 S&W P320 Pistols – SKU 8900160 is the very core of the revolutionary SIG P320 modular handgun platform. Whether you’re a professional shooter, tactical operator, or firearm enthusiast looking to build a custom pistol, this serialized FCU gives you complete control and unmatched flexibility.

Made with precision-engineered components and assembled by SIG Sauer experts, this FCU empowers you to legally build a custom P320 from the ground up with a personalized grip module, slide, and barrel—exactly how you want it.

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What Is a Fire Control Unit (FCU)?

The Fire Control Unit (FCU) is the legal and functional core of the P320 series. It houses the trigger, sear, hammer, and safety mechanisms—essentially the action that makes the gun fire. In SIG Sauer’s modular design, the FCU is also the serialized component, meaning it’s classified as the “firearm” under U.S. law.

This drop-in FCU allows you to fully customize your P320 build using SIG factory or aftermarket parts, without needing to buy an entirely new firearm. It’s ideal for enthusiasts who want to switch calibers, change sizes (Compact, Carry, Full-Size, etc.), or optimize for carry, competition, or duty use.

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Key Features and Benefits

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True Modular Design

• Fully compatible with all P320 grip modules, slides, and barrels for 9mm, .357 SIG, and .40 S&W.

• Enables seamless caliber conversions and configuration changes.

• Compatible with full-size, compact, X-Series, and carry modules.

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Serialized, Legally Transferable Firearm

• The FCU is the legally registered firearm—no need to buy multiple guns.

• Allows you to register just one component while owning multiple configurations.

🛠️

Premium SIG Sauer Craftsmanship

• Manufactured in SIG Sauer’s state-of-the-art facility in Newington, New Hampshire.

• Heat-treated stainless steel chassis with precision internal components.

• Designed for durability, accuracy, and reliability.

🎯

Flat-Faced X-Series Trigger

• Comes with a skeletonized flat-face trigger, preferred for its crisp break and better finger placement.

• Reduces perceived trigger weight and improves control.

🔄

Caliber Conversions

• Easily switch between 9mm, .357 SIG, and .40 S&W with appropriate X-Change Kits.

• One FCU, infinite configurations—your shooting needs evolve, and so can your gun.

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  Why the P320 FCU Is a Game-Changer

  The P320 FCU redefines what it means to own a modular handgun. Most pistols are locked into a fixed frame size and caliber, but with this FCU, you break free from limitations. You can build:

  • A full-size pistol for duty use

  • A compact carry weapon for concealed protection

  • A competition-ready precision firearm

  • A home defense setup optimized for recoil management

  All without buying a completely new firearm.

  This level of modularity was once only available to military and law enforcement units. With SIG Sauer’s innovation, it’s now within reach of civilians, enthusiasts, and competitive shooters.

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  Custom Builds: Unleash Your Inner Gunsmith

  Pair your FCU with:

  • SIG X-Change Kits: These include slides, barrels, and recoil assemblies.

  • Aftermarket grip modules: From Wilson Combat, Icarus Precision, and others.

  • Custom slides: Add optics cuts, porting, or serrations.

  • Barrels: Match-grade threaded barrels for suppressors or comps.

  • Trigger upgrades: Go for lighter pull weights or different shapes.

  • Finishes: Cerakote, DLC, Gold PVD, or custom laser etching.

  Whether you’re aiming to build a minimalist EDC or a high-speed competition piece, the FCU is your blank canvas.

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  Who Should Buy the SIG P320 FCU?

  This product is ideal for:

  • 🔹 DIY builders who want to design a fully custom pistol

  • 🔹 Competitive shooters optimizing their setup

  • 🔹 Tactical professionals switching between mission-specific setups

  • 🔹 Collectors and enthusiasts interested in modular gun tech

  • 🔹 Anyone seeking a cost-effective path to multiple handguns using one serialized core

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  Legal Considerations

  🔒

  Background Check Required

  Because the FCU is a serialized firearm component, it must be transferred through an FFL. This means:

  • You must be 21+ years old.

  • You must pass a federal background check.

  • The FCU will be shipped to your local licensed gun dealer for pickup.

  Note: Always check your local, state, and federal laws regarding firearm assembly and ownership.

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  Why Choose SIG Sauer?

  SIG Sauer is globally respected for precision engineering, innovation, and reliability. With military contracts across the world—including the U.S. Army’s M17 and M18 modular handgun systems—SIG products are battlefield-proven and competition-winning.

  The P320 FCU represents the pinnacle of this innovation, delivering flexibility without compromise. When you choose SIG, you’re choosing a firearm trusted by professionals in the most demanding environments.

  Maintenance & Longevity

  The FCU is designed for long-term performance:

  • Stainless steel chassis resists corrosion

  • Replaceable springs and pins

  • Compatible with factory and enhanced maintenance kits

  • Easy to disassemble for inspection or deep cleaning

  Proper care, lubrication, and occasional part replacement will keep your FCU functioning for tens of thousands of rounds.

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  FAQs

  ❓ Can I use this FCU to build a pistol in 10mm or .45 ACP?

  No. This specific FCU is compatible only with 9mm, .357 SIG, and .40 S&W. .45 ACP P320s use a different FCU.

  ❓ Is this a complete pistol?

  No. This is only the Fire Control Unit. You will need a compatible grip module, slide, barrel, and magazine to complete your build.

  ❓ Do I need a background check?

  Yes. The FCU is a serialized firearm and will require transfer through a Federal Firearms Licensee (FFL) with a background check.

  ❓ Is this FCU compatible with aftermarket parts?

  Absolutely. It works with SIG OEM parts as well as popular aftermarket brands like Wilson Combat, Icarus Precision, ZEV Technologies, and more.

  FIRE CONTROL UNIT

  FIRE CONTROL UNIT

  FIRE CONTROL UNIT

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  Final Thoughts: The Ultimate in Pistol Customization

  The SIG SAUER Complete Fire Control Unit for 9mm/.357 SIG/.40 S&W P320 Pistols – 8900160 is more than a firearm part—it’s a gateway to endless handgun customization possibilities. Whether you’re building your ideal concealed carry pistol, an optics-ready tactical setup, or a sleek competition shooter, it all begins with the FCU.

  Build it your way. Own your style. Trust in SIG.

  FIRE CONTROL UNIT

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  Buy With Confidence

  ✅ Genuine SIG Sauer OEM Product

  ✅ Ships to Your Local FFL Dealer

  ✅ Backed by SIG Sauer Quality Guarantee

  Order yours today and start building the perfect pistol.

  FIRE CONTROL UNIT