This is an easy, permanent way to fit a muzzle device to a specific AK. While a little wobble isn’t a problem, you can grease up the threads to fill in the clearance, if the wobble is to the point where it’s going to lead to problems down the line you might want to consider filing it like this.
And let’s face it, wobbly muzzle brakes might not be any issue at all but is exactly the sort of thing that annoys gun owners and this is a simple way to address it.
While shims and washers will also eliminate wobble, it’s not ideal, especially if your cleaning regimen includes removing the muzzle device and inspecting the crown.
The flipside to this fix is that the muzzle device might need touching up depending on what type of metal its made of.