Originally Posted by BBJones
Tip for crush washers with muzzle devices that need to be timed.
Tighten slowly and back off, repeat until you have almost timed it correctly. Then make final turn to time.
By backing off it allows the crush washer to compress enough that you can actually time the muzzle device. You should never "sand" them to make the muzzle device time properly.
I agree, which is why I've quit using crush washers altogether. When the washer puts your muzzle device 'out of time' by 350º it's impossible to 'tighten, back off' enough to crush it enough without deforming it more than sanding it ever would.
Still, I agree that sanding a washer is a terrible idea. Shims or peel washers are far better.