AT3™ Mil Spec Buffer Tube Kit For AR-15 – 10 Colors Available

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The perfect kit for your next build – at a price that can’t be beat.

This Mil-Spec AR-15 Buffer Tube Kit includes the buffer tube, castle nut, lock plate, 3oz carbine recoil buffer and recoil spring. All parts are designed for easy assembly and compatibility with all your other AR-15 components.  And if you want to get a custom look for your gun, we offer an array of Cerakote finish options to match the buffer tube, castle nut, and endplate.

This kit and its components are backed by the AT3 Lifetime Warranty for guaranteed function.  AT3 cannot warranty against Cerakote™ inconsistencies or the wearing of coatings over time.

Included in the kit

  • 6 position Mil-Spec buffer tube
  • 3oz carbine recoil buffer with T6 anodized aluminum body
  • Steel Buffer Spring
  • Steel castle nut
  • Steel end plate


  • Buffer Tube Diameter: 1.146″ (Mil Spec)
  • Buffer Tube Length: 7 1/4″
  • Buffer Tube Thread type: 1 3/16-16 UN-3B SPECIAL
  • Buffer Tube Material: 6061-T6 Aluminum
  • Spring Type: Carbine length, black coated
  • Castle nut material: Steel
  • End plate material: Steel
  • Recoil spring type: Steel
  • Finish
    • Black: Hardcoat Anodized
    • Flat Dark Earth: H-267 Magpul® Flat Dark Earth
    • OD Green: H-232 Magpul® OD Green
    • Gray: H-188 Magpul® Stealth Grey
    • Pink: H-224 SIG™ Pink
    • Red: H-167 USMC Red
    • Blue: H-171 NRA Blue
    • Burnt Bronze: H-148 Burnt Bronze
    • Tungsten: H-237 Tungsten
    • Titanium: H-170 Titanium
  • Buffer type: 3oz weight, carbine style

Products available on this page:

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

AT3 Lifetime Warranty Logo

All AT3 Tactical Brand Products carry a lifetime warranty against manufacturer’s defects.

This includes AT3 Red Dot SightsHandguardsIron Sights, and any other product that carries the “AT3 Tactical” or “AT3™” name. For other brands (ex. Magpul or Troy), please refer to the manufacturer’s warranty policy.

In the event that your AT3™ product becomes unusable, we will repair or replace the product at no charge to you.

If we cannot repair your product, we will replace it with a product in perfect working order of equal or better physical condition. The warranty is fully transferable, but we may require information about the original purchase to validate the authenticity of the product.

If your product is in need of warranty service, please contact AT3 Tactical to start the process

Our contact info is available here. To expedite processing, please provide your order information and description of the defect.

Please note: The AT3 Lifetime Warranty does not cover loss, theft, intentional damage or cosmetic damage that doesn’t affect the performance of the product.

Customer Reviews

Based on 82 reviews
Isaac Pickett
Good product

Great product. Shipped out super fast and arrived shortly there after. Works great, looks even better

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Bobby Hewitt
AR pistol in 223 ....

Built another AR 80% with a 10" pistol upper because joe said he doesn't like them so if he don't like them I'm gonna build them ...come and take it joe.

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Jerald Akins
Buffer tube assembly

Fast shipping. Perfect fit and functionality. No issues. Recommend

Thanks for sharing your feedback, Jerald! We're glad you're satisfied with your purchase. Cheers!


Exactly what I needed to convert my AR to milspec, good product, quick shipping, would recommend!

Perfect finish.

Helped complete my valentine build. Quick ship, happy customer.

Thanks for sharing your feedback, Jose. We're glad you're satisfied with your purchase. Cheers!