I have shaved the comb on several shotguns over the years to reduce DROP AT FACE, which is all that really matters, by starting about 2" in front of the butt heel, and with a very small block plane, removing very small slivers of wood moving forward toward the nose of the comb, then finishing the final tune with coarse (100 grit wet-or-dry) sandpaper, feathering the work back to the butt for a clean, almost straight line that is imperceptible after the progressive finer grits to a final polish and refinish.
This works great because you don't alter the butt pad or plate. This is also assuming there is enough wood to begin with and you don't need a whole lot. Anything radical is a whole 'nother thing...
JR
