AT3™ MOTHERFU-BAG™ – The BIG AR-15 Lost Parts Kit – Springs, Detents, Wear Parts, and More

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Launch a detent?  Snap a spring?  Don’t get mad, just fix it with this AR-15 Lost Parts Kit!

Alright, so y’all seem to like the FU-BAG.  Like a lot.  Which probably means there’s a lot of little springs, detents, and pins lying around in dark corners around America.  But we’ve heard you asking for more.  More ways to get you out of that hole after you’ve  F***ed Up – Building A Gun.

Here’s our answer.  To better fit the rage we’ve all felt as springs bend, cotter pins break, or when guns just plain stop working right, we’ve come up with a new kit for all those lost and wear parts your gun needs.  The MOTHERFU-Bag contains a big mix of upper and lower parts for the AR-15 that commonly get lost, break, wear out, or just plain bend too far out of whack to use again.

As always, remember to wear your eye protection whenever you’re dealing with parts under spring tension.  Trying to fix an AR with no depth perception isn’t the easiest thing in the world.

American Made Quality

  • All parts meet or exceed military specifications (Mil-Spec)
  • Components are 100% Made in the USA
  • Backed by the AT3 Lifetime Warranty

The MOTHERFU-BAG Includes:

  • Hammer Spring
  • Trigger Spring
  • Disconnector Spring
  • (2) Hammer/Trigger Pin
  • (2) Firing Pin Retainer
  • (3) Gas Ring
  • Extractor O-Ring
  • Extractor Spring
  • Bolt catch plunger
  • Bolt catch roll pin
  • Bolt catch spring
  • Buffer retainer
  • Buffer retainer spring
  • Magazine catch spring
  • Selector detent
  • Selector detent spring
  • (2) Takedown/Pivot pin detent
  • (2) Takedown/Pivot pin detent spring
  • Trigger guard roll pin
  • (2) Gas Tube Roll Pins
  • (1) Adhesive bandage for any other boo-boos you make

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 15 reviews
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C
Carey Maxwell
first time AR-15 builder

As careful as you're going to be, you can count on an essential spring or detent being lost or at least shot across the room and spending 20 minutes looking for it. This bag covers those parts with quality replacements. Whether an experienced builder or a new one, you need to get the MOTHERFU-BAG before you start a new build. The name fits it well.

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

K
Kevin Thompson
Parts kit that all the smalls

I have seen other parts kits out there, this covers more "oops" and" Mother !@#$%&" moments !

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

T
Tim Sanders
Great small parts kit

Whether you have a small part break or sometimes fumble fingers like myself, the "lost and wear" parts kit is a much needed item in your gun room.

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

T
Todd Dewell
Good value

Well pleased. Have already dipped into one of the bags for a part. The bandaid was a nice touch. Would highly recommend.

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

C
Chris Miller
Lost parts

At the range ,out shooting with a friend, taking your gun apart, lose a part ,it's in the bag. Thanks AT3

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