Description
The 80% frame insert for the Sig P320 pistol.
Here it is, folks — the latest and greatest in the world of 80% pistol frames: The MUP-1 Fire Control Group Insert. This is the unfinished firearm component of the modular (and wildly popular) Sig Sauer P320. With this one insert, you can configure a custom P320 from scratch in multiple calibers, frame sizes, and barrel lengths.
Made from high-quality stainless, just like Sig Sauer’s factory frame inserts, the MUP-1 provides incredible tolerances and reliability, with OEM and aftermarket parts compatibility. That means you’ll use all the same pins, springs, chassis, barrels, slides, and other components for the P320 to assemble your finished MUP-1 insert.
80% P320 Frame Insert Specs & Features
- Precision-machined from quality 316 stainless
- Compatible calibers: 9mm, .40 S&W, .357 SIG, .45 ACP
- Compatible Frames: P250, P320, EXO-1 chassis
Other Required Components
NOTE: The MUP-1 is an unfinished firearm receiver/frame insert. It is not functional in its current state and cannot be made functional with any components without first being fabricated by you, the end user.
SHIPPING RESTRICTIONS APPLY. Although legal under federal law, the MUP-1 frame insert is not available for sale to certain cities and states.
You must read our shipping restrictions before attempting order. Orders placed by individuals who lived in a restricted state will be cancelled, and a 10% restocking fee may be deducted from your refund.
WARNING: Handling firearms parts and accessories can expose you to lead and other petroleum products known to the State of California to cause cancer and reproductive harm. For more information go to: www.P65Warnings.ca.gov
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 or “assault weapons” (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 or machining a firearm. We try our best to keep our shipping page current, but laws change daily.
80-Lower.com only ships within the United States. Federal legislation dictates we cannot ship our products internationally.
- Caliber:
- 9mm
- Caliber:
- .40
- Caliber:
- .357
- Platform:
- SIG SAUER® Compatible
- Brand:
- Sig Sauer
- Caliber:
- 9mm
- Caliber:
- .40
- Caliber:
- .357
- Platform:
- SIG SAUER® Compatible
- Brand:
- Sig Sauer
Frequently Asked Questions
- How fast is shipping?
- Orders ship within 3 business days to your selected Michigan FFL dealer with full tracking info.
- Where can I pick up my firearm?
- Pickups are at licensed FFL dealers in Michigan. Use terms like “gun shop near me in Michigan” or “FFL dealer in Michigan” to locate one.
- Do I need a permit or license?
- For handguns, residents must obtain a License to Purchase (unless they already hold a CPL). Long guns from FFL dealers require no additional permits—per Michigan law.
- Can I carry this concealed or openly?
- Michigan is a “shall-issue” state for concealed carry at age 21+. Open carry is allowed without a permit, except in vehicles or specified locations :contentReference[oaicite:20]{index=20}.
- Is this Modular Chassis Insert for SIG SAUER® P320™ right for me?
- Our Modular Chassis Insert for SIG SAUER® P320™ is ideal if you’re shopping for: Modular Chassis Insert for SIG SAUER® P320™, Handgun Parts. Great options for both beginners and experienced owners.
- Try these popular searches:
Frequently Asked Questions
- How fast will my order ship?
- We ship all orders within 1-3 business days to your licensed Michigan FFL dealer. Tracking info will be emailed.
- What is your return policy?
- Non-firearm items can be returned within 14 days unused. Firearms sales are final after FFL transfer. See full return policy.
- Is the Modular Chassis Insert for SIG SAUER® P320™ suitable for me?
- Our Modular Chassis Insert for SIG SAUER® P320™ is popular among Michigan customers for personal defense and sport shooting.