AR-15 Bolt Catch Spring – Mil-Spec Detent Spring for Reliable Retention

The AR-15 bolt catch spring may be one of the smallest parts in your lower receiver, but it plays a critical role in function and reliability. Whether you’re building a new AR-15 from scratch or replacing worn components, this mil-spec detent spring ensures proper tension for your bolt catch — the part responsible for holding the bolt open after the last round.

Crafted to exacting standards, this AR-15 bolt catch detent spring is heat-treated for durability and precision-fit to match all standard AR-15 lower receivers. If you're chasing flawless bolt lock-back and want your build to function like factory-new, this is the spring you need.

It’s also a smart addition to any AR-15 lower parts kit or small parts backup pouch — because let’s face it, springs like this have a way of launching across the garage mid-build.

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🔧 Product Features:

• ✅ Mil-spec compatible with AR-15 lower receivers

• ✅ Precision-made for smooth bolt catch engagement

• ✅ Heat-treated spring steel for long-lasting performance

• ✅ Perfect for new builds, repairs, or spare parts kits

• ✅ Works with standard bolt catch plungers and roll pins

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🔗 Related AR-15 Build Components

Need more than just the spring? Get everything you need for a clean bolt catch install:

• Complete your setup with a full AR-15 lower parts kit
• Use an AR-15 build tool kit to make assembly easier
• Pair with a bolt catch plunger and bolt catch roll pin
• For smooth installation, we recommend a roll pin punch set or the Deltac punch set for AR builds
• Want to do it right the first time? Explore our armorer’s tool kits

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🔍 Frequently Asked Questions (FAQs)

Q: Is this bolt catch spring compatible with all AR-15 lowers?
A: Yes — this spring meets mil-spec standards and is compatible with all standard AR-15 lower receivers.

Q: Can I use this spring in a .308 or AR-10 build?
A: This spring is designed specifically for AR-15 platforms. While it may fit some AR-10 receivers, always check compatibility with the manufacturer.

Q: What other parts do I need to install a bolt catch?
A: You'll need the bolt catch itself, the bolt catch plunger, the roll pin, and this spring. We recommend using a roll pin punch set for a smooth install.

Q: Is this spring included in a lower parts kit?
A: Yes, but it's always a good idea to keep extras on hand — these tiny springs are easy to lose during assembly.

Q: How do I install the bolt catch spring?
A: Insert the spring into the bolt catch detent hole in the receiver, followed by