• Wishlist
  • My Account
    • Login
    • Sign Up
  • 0
Toggle menu
ColtParts.com
×
×

    Shop By Category

  • Accessories
    • Sights
    • Slings
    • Suppressors
    • Vertical Grips
  • Books & Manuals
  • Firearms
    • Handguns
    • Rifles
    • Legacy Vault
  • Magazines
    • Magazine Accessories
  • Pistol Parts
  • Tools
  • Rifle Parts
    • Buffer System
    • Handguard Rails
    • Barrels
    • Bolts
    • Upper Parts
    • Stocks
    • Grips
    • Lower Parts
    • Upper Receivers
    • Lower Receivers
  • Shop By Brand

  • Colt
  • Magpul
  • AU
  • Knights Armament
  • SureFire
  • Blue Force Gear
  • Fix It Sticks
  • B&T
  • B5 Systems
  • EOTech
  • MaTech
  • Simunition
  • Viking Tactics
  • View all Brands
  • Main Menu

  • Rifle Parts
  • Pistol Parts
  • Accessories
  • Magazines
  • Books & Manuals
  • Shipping & Returns
  • Contact Us
  • RFQ
  • Connect with Us:
  • Gift Certificates
  • Login or Sign Up

    Shop By Category

  • Accessories
    • Sights
    • Slings
    • Suppressors
    • Vertical Grips
  • Books & Manuals
  • Firearms
    • Handguns
    • Rifles
    • Legacy Vault
  • Magazines
    • Magazine Accessories
  • Pistol Parts
  • Tools
  • Rifle Parts
    • Buffer System
    • Handguard Rails
    • Barrels
    • Bolts
    • Upper Parts
    • Stocks
    • Grips
    • Lower Parts
    • Upper Receivers
    • Lower Receivers
  • Shop By Brand

  • Colt
  • Magpul
  • AU
  • Knights Armament
  • SureFire
  • Blue Force Gear
  • Fix It Sticks
  • B&T
  • B5 Systems
  • EOTech
  • MaTech
  • Simunition
  • Viking Tactics
  • View all Brands
  • Main Menu

  • Rifle Parts
  • Pistol Parts
  • Accessories
  • Magazines
  • Books & Manuals
  • Shipping & Returns
  • Contact Us
  • RFQ
  • Connect with Us:
  • Gift Certificates
  • Login or Sign Up

Shop by Category

  • Accessories
    • Sights
    • Slings
    • Suppressors
    • Vertical Grips
  • Books & Manuals
  • Firearms
    • Handguns
    • Rifles
    • Legacy Vault
  • Magazines
    • Magazine Accessories
  • Pistol Parts
  • Tools
  • Rifle Parts
    • Buffer System
    • Handguard Rails
    • Barrels
    • Bolts
    • Upper Parts
    • Stocks
    • Grips
    • Lower Parts
    • Upper Receivers
    • Lower Receivers
  • Shop by Brand

  • Colt
  • Magpul
  • AU
  • Knights Armament
  • SureFire
  • Blue Force Gear
  • Fix It Sticks
  • B&T
  • B5 Systems
  • EOTech
  • View all Brands
    • Home
    • Rifle Parts
    • Buffer System
    • AU Mil-Spec Castle Nut for M4/AR15
  • AU Mil-Spec Castle Nut for M4/AR15
  • AU Mil-Spec Castle Nut for M4/AR15

    AU Mil-Spec Castle Nut for M4/AR15

    AU

    MSRP:
    Price: $9.95
    SALE: $2.95
    (You save )
    (1 review) Write a Review
    SKU:
    MSCN-AR15
    Bulk Pricing:
    Buy in bulk and save

    Bulk discount rates

    ×

    Below are the available bulk discount rates for each individual item when you purchase a certain amount

    • Buy 100 or above and pay only $2.00 each

    Adding to cart… category.add_cart_announcement
    Add to Wish List
    • Create New Wish List
    • Facebook
    • Email
    • Print
    • Twitter
    • Overview
    • Reviews

    Product Description

    AU's receiver extension castle nut for M4/AR15 type rifles

    Product Videos

    Custom Field

    Product Reviews

    Write a Review

    Write a Review

    ×
    AU Mil-Spec Castle Nut for M4/AR15
    AU
    AU Mil-Spec Castle Nut for M4/AR15

    1 Review Hide Reviews Show Reviews

    • 5
      quality product

      Posted by stimpson j. cat on 9th Mar 2026

      highly engineered product made from space age microspheres that also reduces the cyclic rate of my farting trigger. thanks A.U.!!!

    Recommended

    • SALE
      AU Mil-Spec AR15/M4 Pistol Grip AU Mil-Spec AR15/M4 Pistol Grip
      Quick view Details

      AU

      |

      sku: MSPG-AR15

      AU Mil-Spec AR15/M4 Pistol Grip

      MSRP:
      Price: $12.00
      SALE: $2.95
      Out of Stock
    • SALE
      Mil-Spec M4/AR15 Carbine Buffer Action Spring Mil-Spec M4/AR15 Carbine Buffer Action Spring
      Quick view Details

      AU

      |

      sku: MSCBAS-AR15

      AU Mil-Spec M4/AR15 Carbine Buffer Action Spring

      MSRP:
      Price: $5.95
      SALE: $2.50
      Add to Cart
    • Colt M4/AR15 Receiver Extension Castle Nut Colt M4/AR15 Receiver Extension Castle Nut
      Quick view Details

      Colt

      |

      sku: 9390020

      Colt M4/AR15 Receiver Extension Castle Nut

      MSRP:
      SALE: $9.95
      Add to Cart
    • Colt AR15/M4 Mil-Spec Lower Parts Kit Colt AR15/M4 Mil-Spec Lower Parts Kit
      Quick view Details

      Colt

      |

      sku: SPK99796

      Colt AR15/M4 Mil-Spec Lower Parts Kit

      MSRP:
      SALE: $69.00
      Out of Stock
    • Colt AR15/M4 Mil-Spec Fire Control Parts Kit Colt AR15/M4 Mil-Spec Fire Control Parts Kit
      Quick view Details

      Colt

      |

      sku: SPK99795

      Colt AR15/M4 Mil-Spec Fire Control Parts Kit

      MSRP:
      SALE: $75.00
      Out of Stock
    ×
    ×
    Join Our Mailing List To Unlock Special Discounts & Offers !
    Contact Us
    2061 Pabco Rd
    Henderson NV 89011
    Accounts & Orders
    • Wishlist
    • Login or Sign Up
    • Shipping & Returns
    • Product Warranty Registration
    • Find Colt Serial Number
    Quick Links
    • Rifle Parts
    • Pistol Parts
    • Accessories
    • Magazines
    • Books & Manuals
    • Shipping & Returns
    • Contact Us
    • RFQ
    Connect with Us:
    • © ColtParts.com

    Disclaimer: “COLT” is a federally registered trademark of Colt's Manufacturing Company, LLC and is one of many trademarks owned by Colt's Manufacturing Company, LLC or Colt/CZ Group SE. ColtParts.com is not affiliated with nor endorsed by Colt's Manufacturing Company, LLC or Colt/CZ Group SE.