SIG SAUER® Compatible Pistol Kit

SIG SAUER® Compatible Pistol Kit

Build a modular Sig P320 handgun with a quality, US-made 80% kit and OEM components.

The P320's capable of chambering three cartridges in four configurations. It's effectively various handguns in one, providing a platform for daily carry and range days alike. But you don't have to spend a premium buying a "retail" P320. Instead, you can legally build one from scratch. Our Sig Sauer P320 80% pistol kits provide all the tools and parts you need to do just that, with no experience or specialty tools required.

What's Included With Each Kit

  • Modular Universal Pistol 1 (MUP1) FCU: The basis of your P320 platform. This is the 80% 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 parts kit: Required to assemble your FCU into a ready-to-fire insert.
  • The P320 “exoskeleton”: A factory slide with night sights (includes barrel and guide rod/recoil spring assembly) , a factory grip module (frame).
  • Carrying Case: A simple, convenient carrying case to protect your newly minted P320.

Not Considered a Firearm, Legal to Build

Like an 80% lower, the 80% FCU is legal to buy, ship, own, and build under federal law. You don't need to transfer it through an FFL, pay any dealer fees, or conduct a background check with any paperwork. Since the FCU in these kits isn't fabricated, it's not functional as a firearm and the ATF instead recognizes it as a receiver blank.

Building your P320 from scratch requires no FFL license or paperwork under federal law, either. Once finished, you'll be the proud owner of a new modular handgun that can accept any factory or aftermarket parts, barrels, grip modules, and all available configurations.

State Laws May Vary

Contrary to federal law, some states have either restricted or banned the sale, transfer, and ownership of 80% lowers, firearm blanks, and other gun parts. Because of these restrictions, we cannot ship our products to certain states. Please confirm whether your state is restricted on our Shipping & Return Policy before placing an order. We cannot fulfill orders to restricted states if placed.

Completing Your P320 80% FCU

Some basic fabrication steps are required for making the FCU into a functional firearm. Using a Dremel and small cut-off wheel, you'll cut the trigger slot and slide rails. A simple hammer is required to bend some metal tabs for the parts kit and slide to install, too. Lastly, you'll need to drill various pin holes using the provided drill bits with the pistol kit. Once finished, you can assemble your FCU and install your P320's other components.


DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

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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.