Let's face it, there are some things you can get away with until you step up to a .30 caliber weapon. Not saying that a 5.56 is a lesser gun, but when you go bigger stresses do increase. That means every part of your .30 caliber rifle has to be up to the task. Heaver recoil means more abuse and vibration ringing through every part, even your muzzle device.
Do you really trust a low quality 5/8-24 crush washer to keep your muzzle device where it's supposed to be? Think about it, a 5/8-24 crush washer is designed to, well be crushed. How many times have you tried to back that muzzle brake off by hand after tightening it down on a crush washer? You know you have, I've done it myself just to check if it was tight. In the back of your mind, you just don't' trust that 5/8-24 crush washer, especially when it comes to your AR-10. However, you can believe in a Precision Armament 5/8-24 muzzle device alignment system.
When you install a muzzle device, chances are good it won't crank down exactly true. Many muzzle devices have to be timed in order to perform. Instead of a crush washer that only should be good enough, what you need is a 5/8-24 muzzle device alignment system that you know is right. Precision Armament adopted the approach of just using the exact part you need to make it right. You simply choose one Precision Armament Accu-Washer, the one you need to do the job. Torque down that muzzle brake and forget about it. You shouldn't guess or hope, you have to know that it's right.