Sig Sauer Custom Works P320 Fire Control Unit Multi Caliber 8900160

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Build your own P320 with the SIG Sauer Custom Works P320 Fire Control Unit. The P320 was built with modularity in mind allowing you to easily swap out grip frames, slides, and even change calibers to easily meet your needs. Now you can start from the ground up with a premium FCU. The SIG P320 FCU features a Titanium Nitride finish and a flat faces skeletonized trigger. The Titanium Nitride finish is exclusive to this fire control unit and includes a custom serial number. It is compatible with all 9mm/357SIG/40S&W P320 post upgrade accessories. Get started on your new custom build today.


  • Titanium Nitride frame and trigger
  • Flat faces skeletonized trigger
  • Custom FCU serial number
  • Ambidextrous slide release
  • Compatible with all 9mm/357SIG/40S&W P320 post upgrade accessories

Sig Sauer is a world-renowned firearms manufacturer with a rich history of innovation and design leadership. No other firearms manufacturer is so highly regarded and so universally respected for the quality, reliability, and safety of its products. Since 1864 they have expanded their product line to include suppressors, optics, ammo, and airguns to provide customers with a greater range of firearms and equipment.


Categories: Pistols
Condition: New
Manufacturer: SIG SAUER
Model: Fire Control Unit
SKU: 798681633319
MPN: 8900160
UPC: 798681633319
Vendor: Gunprime
Reviews (3)
By allhailthetail on 07/09/22
Good Price, Arrived Promptly

SIG needs no introduction. The P320's design is amazing and the modularity makes upgrading the pistol convenient and affordable. I needed this for another build and the FCU is the 'firearm' as far as the ATF is concerned.

It arrived in a well-padded box, lightly lubricated to protect the metal components from rusting. It fits perfectly and performs identically to my other SIG.

Great find and gun prime made buying this easy. I'd use them again. They shipped quickly and were a hassle free experience.

By Marshall Hinton on 06/21/21
Excellent Experience

Before I give my review, I want to go on record and let the world know that no dealer had this product in stock. I have been trying to find this product since Sig Sauer rolled it out. I immediately assembled a S&W 40 cal full. I had the kit. I was waiting to purchase the FCU. I will probably buy it again and build a one-of-a kind custom pistol.

By P320 FCU on 04/22/21
High Quality Product

Exceptional fire control unit! Been looking for this ‘foundation’ piece since sig first announced it
Have just built it into an M17 and customization choices from here are almost endless!!

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