Pistol Build Kit - SIG SAUER® P320 Compatible / 9mm (Full-Sized, Black) w/ Free Carry Case



If you're looking to build your own full-sized pistol, then raise the bar.  We now offer the Sig Sauer® compatible full-sized P320.  This genius thing about the P320 is the fact that you can change its size for whatever your carry need.

Sig Sauer® P320 Modularity

The only part of the P320 that's legally considered the firearm is the fire control group, or the MUP1.  This means you can later simply take it out of your full-sized P320 build and then swap out parts to make it an entirely different size altogether.  The result is a single pistol you can use in place of all others in all types of situations.  

Modular Universal Pistol 1 (MUP1) insert

Just like  the 80% lower receiver for the AR-15, we’re excited to offer the MUP1 insert for the Sig P320. This is JSD Supply's great answer to your calls for an 80% Fire Control Unit insert. With the included jig, tool bits and instructions, all it takes is an afternoon with a few hand tools to fabricate your own, functional FCU.

P320 Lower Parts & Build Kit

With the 80% insert drilled and fabricated, final assembly of the FCU means installing the included P320 lower parts kit. Once installed, you’ll be the proud owner of a modular, ready-to-fire Sig Sauer® P320! To get you off the workbench and onto the firing line, we also included a full-size 9MM P320 build kit:

  • 9mm Full Size Complete Slide
  • Full Size Medium Grip Module
  • Barrel & Recoil Spring Assembly
  • Night sights
  • Carrying case

The platform that fits 9MM parts will also accept .357 SIG and .40-S&W P320 parts.


  • Modular Universal Pistol 1 (MUP1) insert: The basis of your P320 platform. This is the Fire Control Unit you’ll need to fabricate with the included jig. This process enables you to finish your P320 on your own without the need to go through an FFL.
  • The Jig:  Required to finish your MUP1 80% insert. It takes away the guesswork by showing you where to drill and what to fabricate. No experience necessary.
  • The lower parts kit:  Required to assemble your FCU into a ready-to-fire insert.
  • The P320 “exoskeleton”:  A full-size slide with night sights (includes barrel and guide rod/recoil spring assembly) , a full-sized grip module (frame).
  • Carrying Case:  A simple, convenient carrying case to protect your newly minted P320.


No FFL required  Made in the USA  Lifetime Warranty

Shipping Restrictions

AR-15Lowerreceivers.com only ships within the United States. Federal legislation dictates we cannot ship our products internationally. Shipping of various parts and/or accessories are prohibited to states and locales (ie New Jersey, California, New York, etc…) with restrictions against certain parts and/or accessories (i.e. states with high-capacity magazine restrictions, manufacturing of semi-automatic weapons, etc..). It is your responsibility to be aware of your local firearms laws before purchasing from our website. We try our best to keep our shipping page current, but laws change daily.

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.