Crush Washer

A crush washer is a deformable metal washer that sits between your muzzle device and barrel shoulder, providing proper alignment and preventing loosening during use. Made from soft steel or copper, these washers compress when you torque down your muzzle brake or flash hider, creating a gas-tight seal and allowing precise timing of your muzzle device.

Why Crush Washers Matter for Your Build

When you install a muzzle device on your AR-15 barrel, you need it positioned correctly: ports facing up on a brake, prongs oriented properly on a flash hider. The crush washer lets you achieve this alignment by deforming as you tighten the device. Without it, your muzzle device might not time correctly or could work loose under firing conditions.

The washer typically compresses 0.002 to 0.005 inches when properly installed with 15-20 ft-lbs of torque. This compression fills any gaps between thread surfaces and creates tension that resists loosening from vibration and heat cycles.

Installation Considerations

Always install crush washers with the tapered side facing the muzzle device. You’ll feel increasing resistance as you tighten; this is the washer deforming. Most builders find they need to turn the device 90 to 180 degrees past hand-tight to achieve proper timing and torque.

Important exceptions: Never use a crush washer with a suppressor mount or precision devices requiring consistent shoulder contact. These applications call for shims or peel washers instead, as crush washers can cause alignment issues affecting accuracy or suppressor performance.

When selecting components for your build using the AR15 Outfitters builder, remember that most muzzle devices include a crush washer. However, if you’re planning a suppressor-ready build, factor in appropriate shim sets or timing washers instead.