Fast, Free Shipping on Orders over $139

Quality Parts that Don't Break the Bank

4.8 Stars from 20.7K Reviews

Friendly Service from Firearms Experts

Popular:

handguard magpul buffer tube bcg charging handle foregrip pmag sling stock buffer

Sign In Create an Account

Cart

Sign In Create Account

Shop
Shop All 5,700+ firearms & accessories
- Upper Receiver Components
  Shop All Upper Receiver Components 1,500+ products
- Lower Receiver Components
  Shop All Lower Receiver Components 1,100+ products
- Sights, Optics, Lights, Lasers
  Shop All Sights, Optics, Lights, Lasers 583 products
- Firearms
  Shop All Firearms 546 products
- Build Kits and Assemblies
  Shop All Build Kits and Assemblies 79 products
- Handgun Parts
  Shop All Handgun Parts 568 products
- Magazines
  Shop All Magazines 377 products
- Gear, Tools & Accessories
  Shop All Gear, Tools & Accessories 765 products
- More Ways to Shop
  Shop All More Ways to Shop 422 products
  - Top Sellers
  - New Products
  - Shop By Color
    Shop All Shop By Color
    
    Flat Dark Earth
    
    OD Green
    
    Red
    
    Gray
    
    Blue
    
    Burnt Bronze
    
    Tungsten
    
    Pink
    
    Titanium
    
    Coyote Brown
  - Shop By Caliber
    Shop All Shop By Caliber
    
    .300 Blackout
    
    .308 AR-10
    
    9mm
    
    7.62x39
    
    .350 Legend
    
    6.5 Grendel
    
    6mm ARC
    
    .450 Bushmaster
    
    .458 SOCOM
    
    5.7x28
    
    6.8 SPC
  - AR-10 Parts
  - Parts by Firearm
  - California Compliant
Sales
Daily Deals
Brands
Shop All Brands
Videos
What's New?
AT3 AR Academy
Resources
About AT3

Fast, Free Shipping on Orders over $139

Quality Parts that Don't Break the Bank

4.8 Stars from 20.7K Reviews

Home > Pistol Frame Parts - Sig Sauer

Sig Sauer Pistol Frame Parts

1 product Sort products SortBest match

Filters

Caliber

.40 S&W1 9mm1

Sort

Best match Popularity Rating Latest Price low to high Price high to low

Availability

On sale

Price

1 product across Sort products SortBest match

Sig Sauer P320 FCU – Fire Control Unit – Black

$349.99

In stock

Shop by category

1,580

Shop all Upper Receiver Components1,580
Handguards & Quad Rails
Complete Uppers
Front Grips
Upper Receivers & Parts
Barrels
Muzzle Devices
Charging Handles
Bolt Carrier Groups
Gas Blocks & Tubes
Handguard Accessories

1,160

Shop all Lower Receiver Components1,160
Buttstocks
Lower Parts & Kits
Triggers
Lower Receivers
Buffer Tubes & Buffer Parts
Pistol Grips
Magazines
Pistol Braces

583

Shop all Sights, Optics, Lights, Lasers583
Red Dot Sights
Lights and Lasers
Scopes
Red Dot Magnifiers
Iron Sights
Optic Mounts

546

Shop all Firearms546
Lower Receivers
Rifles
Handguns
AR-10 Lower Receivers
Shotguns

79

Shop all Build Kits and Assemblies79
Complete Uppers
Furniture Kits
Dream Gun Build Kits
Color Upgrade Kits
AR15 Rifle Build Kits
Lower Build Kits
Upper Receiver Kits
Stock Kits with Buffer Tube
Complete Lower Receivers

568

Shop all Handgun Parts568
Glock 19 Parts
Glock 43x Parts
Glock 17 Parts
Glock 48 Parts
All Glock models
Sig Sauer
Springfield
Handgun Magazines
Pistol Chassis
Handgun Barrels
Pistol Slide Parts
Optic Mounting Plates

377

Shop all Magazines377
Rifle Magazines
Pistol Magazines
Magazine Accessories

765

Shop all Gear, Tools & Accessories765
Tools & Cleaning
Slings & Mounts
Bipods, Sticks, and Rests
All Other Products
Tactical Gear
Rifle Cases
Conversion Kits (.22 & More)
Eye and Ear Protection

Build the ultimate AR.

Get the deals first

Sales, new parts and AR Academy articles. No spam, unsubscribe any time.

Enter Your Best Email *

Website

Help

Contact AT3
FAQ
Returns
Shipping
Lifetime warranty
Accessibility

Shop

Sale
Daily Deals
Clearance
What's new
Shop by color
Gun Bucks rewards
Military & law enforcement discount
Become a Dealer
Dealer portal

About

About AT3
AR Academy
Installation Videos
Free AR e-book
Affiliate program
Careers

Questions about a build? AR experts answer the phone and the chat.

1-888-329-3504

© 2026, AT3 Tactical LLC · 5450 Quam Ave NE, Suite 140, St Michael MN 55376 (not open to the public) · Privacy · Terms

Popular:

handguard magpul buffer tube bcg charging handle foregrip pmag sling stock buffer

Sign in

Orders, tracking, Gun Bucks and saved addresses.

Email

Password

Keep me signed in

Reset your password

We'll email you a link. It expires in 24 hours.

Email

Check your email

New to AT3? Create an account

Create an account

Track orders, earn Gun Bucks on every purchase, check out faster.

First name

Last name

Email

Password 8+ characters with at least one letter and one number.

Email me deals, new gear and Gun Bucks updates

By creating an account you agree to the Terms of Use and Privacy Policy.

Welcome,

Continue shopping

Go to my account

Already have an account? Sign in

Your cart

Subtotal

View cart Checkout