Oops Kit Lower Parts

Product Description

The Anderson Arms AR-15 Oops Kit is a collection of the small, essential lower receiver parts that often go missing during a build or need replacement after installation mistakes.

This kit addresses the most common problem AR builders face: a complete build stalled because one detent rolled under the bench or a spring launched across the room. Instead of ordering a full lower parts kit for parts you already have, an oops kit gives you just the small components that tend to disappear or break.

Whether you are finishing your first lower or you have built a dozen rifles, keeping an oops kit on hand saves time and frustration.

Key Facts

• Brand: Anderson Arms
• Product Name: Oops Kit Lower Parts
• SKU: AM-oopskit
• Category: Lower Parts

What an AR-15 Oops Kit Replaces

An oops kit typically contains detents, springs, and pins—the parts that are easy to lose during lower receiver assembly. Detents are tiny cylindrical parts that hold pins in place and provide spring tension. They are notorious for launching across the garage when a punch slips or a builder releases hand pressure too soon.

Springs wear out, break, or lose tension if over-compressed during installation. Pins can bend if driven in at the wrong angle. Builders often discover one missing piece only after they have cleaned up and put tools away. An oops kit solves that problem without the cost and excess inventory of a second full parts kit.

If you are assembling multiple lowers or maintaining several rifles, an oops kit is cheap insurance. Send us a message if you need help identifying which parts you are missing.

Oops Kit vs. Complete Lower Parts Kit

A complete lower parts kit contains every component needed to finish a stripped lower receiver: trigger group, hammer, disconnector, selector, magazine catch, bolt catch, buffer retainer, takedown pins, and all associated springs and detents. An oops kit contains only the small parts—usually detents, springs, and pins—that you need when the big parts are already installed or accounted for.

Buy a complete kit when you are starting from a stripped lower. Buy an oops kit when you dropped a detent, broke a spring, or want spares on hand during a build session. The oops kit does not replace trigger components, selector levers, or catches—it covers the hardware that keeps those parts in place.

Who Should Keep an Oops Kit on Hand

If you build or maintain AR-15 rifles, an oops kit belongs in your parts drawer. First-time builders often underestimate how easily detents and springs disappear. Experienced builders know to order an oops kit with every new lower build because the cost of a missing detent is a delayed project and a second shipping charge.

Gunsmiths and armorers keep several oops kits in stock because detents and springs are wear items on high-round-count rifles. If you are installing upgraded triggers or selectors, you may reuse some original parts but need fresh detents and springs for proper fitment and tension. The oops kit covers those gaps without waste.

Ordering from Western Sport

Order online and it ships straight to your door. Western Sport has been a licensed FFL/SOT dealer since 2007, and everything we sell carries the full manufacturer warranty. Questions before you order? Send us a message.

Frequently Asked Questions

Q: What is an AR oops kit used for?

A: An AR oops kit is used to replace small lower receiver parts—typically detents, springs, and pins—that are lost, broken, or worn during assembly or maintenance. It gives you the most commonly needed replacement parts without buying a full lower parts kit.

Q: Will the Anderson oops kit work with any AR-15 lower receiver?

A: The Anderson oops kit is designed for standard mil-spec AR-15 lower receivers. Detents, springs, and pins are industry-standard parts that fit most lowers, but Send us a message if you are building a non-standard or billet lower to confirm compatibility before ordering.

Q: Is an oops kit the same as a complete lower parts kit?

A: No, an oops kit contains only small parts like detents, springs, and pins. A complete lower parts kit contains the trigger group, hammer, selector, magazine catch, bolt catch, buffer retainer, and all associated hardware needed to finish a stripped lower.

Q: Can I use an oops kit to finish a stripped lower receiver?

A: No, an oops kit does not contain the trigger components, selector lever, catches, or pins needed to complete a stripped lower. You need a complete lower parts kit for that. Use an oops kit to replace missing or damaged small parts during or after a build.

Q: How do I know which parts are in the Anderson Arms oops kit?

A: Send us a message to confirm the exact parts list for the Anderson Arms oops kit. Part counts and contents vary by manufacturer, and confirming details before ordering ensures you get what your build requires.

Q: Do I need an FFL transfer to buy an oops kit in Texas?

A: No, AR-15 lower parts like detents, springs, and pins are not regulated firearm components and do not require an FFL transfer. You can order an oops kit and have it shipped directly or pick it up at Western Sportwithout transfer paperwork.