When upgrading or customizing your AR-15, one of the most common questions we hear at ShootersGate is:

“Do I need a MIL-Spec or Commercial buffer tube?”

It’s a small detail with big consequences. Choosing the wrong one could mean your stock doesn’t fit—or worse, doesn’t function properly.

Let’s break it down and make sure you’re dialed in before your next build or upgrade.

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What’s a Buffer Tube?

Also called a receiver extension, the buffer tube connects your AR stock to the lower receiver and houses the buffer and recoil spring. It’s essential to your rifle’s function—and your comfort.

But buffer tubes aren’t one-size-fits-all. There are two main types:

• MIL-Spec (Military Specification)

• Commercial

Understanding the difference helps you match your buffer tube and stock perfectly.

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1. Size & Dimensions (The Most Important Difference)

They are NOT cross-compatible. A MIL-Spec stock won’t properly fit on a Commercial tube, and vice versa.

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2. Materials & Durability

• MIL-Spec tubes are typically made from 7075-T6 forged aluminum—a strong, military-grade material used in aircraft and defense industries.

• Commercial tubes are usually made from 6061-T6 aluminum, which is still durable but less robust.

If you're building a duty rifle, using your AR for home defense, or just want the best performance, MIL-Spec is usually the way to go.

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3. Price & Practical Use

• MIL-Spec

  • Slightly higher cost

  • Trusted by military and law enforcement

  • Greater variety of compatible stocks and accessories

• Commercial

  • More budget-friendly

  • Suitable for casual or range-only rifles

  • Fewer stock options available

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How to Tell Which One You Have

Here’s how to quickly identify your buffer tube:

• Flat rear end + thinner diameter = MIL-Spec

• Slanted rear end + slightly thicker diameter = Commercial

Still unsure? Grab a caliper and measure the tube diameter:

• 1.14" → MIL-Spec

• 1.17" → Commercial

Or just ask us at ShootersGate—we’re happy to help you identify your setup.

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Pro Tip: Stick With MIL-Spec for Future Compatibility

Most premium stocks and accessories are made to fit MIL-Spec. If you’re starting fresh, we highly recommend going that route to give yourself more upgrade options down the line.

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Ready to Upgrade Your Buffer Tube or Stock?

Check out our full selection of MIL-Spec Buffer Tubes, Stocks, and AR Build Kits right here on ShootersGate.com.

Whether you're building your first AR or your fifth, we’ve got the gear and guidance to make it flawless.