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How to Install a Crush Washer on an AR‑15 Muzzle Device

Installing a muzzle device with a crush washer is a simple yet critical step when assembling your AR‑15 barrel. Follow this guide to ensure proper alignment, torque, and reliability—whether you're installing a flash hider, compensator, or brake.

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🧰 Tools & Parts You'll Need

• AR‑15 barrel with muzzle threads
• Crush washer (tapered toward receiver)
• Muzzle device (flash hider, brake, compensator)
• Hand-tightening and torque wrench (optional, 15–20 ft‑lb range)
• Wrench or armorer’s tool

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🔧 Installation Steps

1. Orient the Crush Washer Correctly

Put the crush washer on the muzzle with the tapered side toward the receiver shoulder—this ensures it will flatten out under torque and allow proper device alignment.

2. Hand‑Tighten the Muzzle Device

Thread the muzzle device onto the barrel snugly by hand until it seats against the washer. Don’t force alignment—this is just preparing for the next step.

3. Align and Torque

Using your wrench or torque tool, tighten the muzzle device until it lines up at the correct orientation (for example, ports at 11:00 or 6:00 depending on device type)—typically within 450° of rotation from the starting point.
Stop tightening once aligned; most expert recommendations cap torque around 20 ft‑lb to avoid over-crushing

4. Avoid Bottoming Out

If the device bottoms out before aligned, do not continue cranking—that damages the washer. Instead, replace the washer or pre‑crush it slightly before reinstallation.

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💬 Pro Tips & Community Advice

From builders on r/ar15:

“Crush washers for AR muzzle devices are supposed to allow for ~450 degrees revolution… tighten by hand then use a wrench to align it.”

And advice on torque limits:

“If your torque wrench is camming out at 20 ft‑lb and it’s just a couple degrees off, then I would go ahead and put on a bit more torque and go for it.”

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🛠️ Tools & Parts to Complete Your Muzzle Device Install

Once you know how to properly install a crush washer, make sure you’re using high-quality parts and tools to get the job done right:

• AR-15 crush washers – Essential for proper muzzle device timing and alignment
• AR-15 muzzle devices – Shop flash hiders, compensators, and brakes
• AR-15 flash hiders – Reduce muzzle flash and protect your vision
• AR-15 compensators – Improve accuracy by reducing muzzle rise
• AR-15 muzzle brakes – Minimize recoil for faster follow-up shots
• AR-15 gunsmithing tools – Install parts the safe and correct way
• Armorer’s tool kits – Complete sets for serious builders and tinkerers

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✅ Frequently Asked Questions

Q: Which way should the crush washer taper face?
A: The tapered side should face the receiver to ensure proper crush and timing.

Q: How many degrees can I rotate the device?
A: Most crush washers allow for up to 450° of wrap to achieve alignment—hand-tighten first, then align with a wrench.

Q: What torque spec should I use?
A: Use 15–20 ft‑lb of torque. Don’t exceed this unless absolutely necessary to align.

Q: What if the device bottoms out before alignment?
A: Do not tighten further. Use a new crush washer or pre-crush the washer manually before reinstalling.

Q: Is a crush washer better than a peel washer or lock nut?
A: Crush washers are simple and reliable for a tight fit; peel washers offer more precise timing, while lock nuts require space and are less common for standard AR-15 builds.

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🧠 Why This Method Works

Following this process ensures your muzzle device aligns correctly without over-torquing the barrel threads or damaging mating surfaces. It's the method recommended by armorers and long-time builders to prevent premature wear, maintain accuracy, and ensure consistent timing.