Hello!
Are crush washer necessary for flash hiders? Why is there a crush washer on every AR? Is just to line up the Flash hider/Muzzle brake? Or does it serve a special purpose?
It depends on the flash hider. Many designs do not require a crush washer, while others do. Consult your manufacturer’s instructions to be sure.
A crush washer is a small, flat disc that is placed between the muzzle device and barrel of a firearm. Its primary purpose is to evenly distribute the pressure of the device against the barrel, in order to prevent any damage or rotation of the barrel that could affect accuracy. Some muzzle devices, such as flash hiders, do not require a crush washer for proper installation, but others do. If you are unsure whether or not your firearm requires one, consult your manufacturer’s instructions before proceeding with installation.