Since one can't magically produce proper adjusting tools for all possible sights and muzzle diameters, and can hardly take the workshop to the range when trying out something new, I confess to using a fair amount of careful and controlled bang myself. Tools: a light ball-pene hammer and a piece of brass rod! It is important to have the sight block resting on something solid - such as a another brass block - so that you can control the blow and feel when the blade moves. Doing it "freehand" is very chancy. If you want really fine adjustments, say a couple of 0.001", then a small toolmaker's cramp will do the trick.
In all cases, you need something like a brass block between the object applying the force and the sight blade/block to avoid marring the sight blade and/or the sight block! Brass is good, aluminium can be quite "scratchy".