I was under the assumption that you could VERY LIGHTLY try to point up the point on the trigger where it engages the SA notch (like 2-3 strokes on a hard stone, and pray) but that you should NEVER touch the SA notch on the hammer. This was due to the case hardening if I recall correctly. The theory was you would get into the softer inner metal, resulting in a soft on soft engagement surface which would of course wear quickly.

I am certainly not a gunsmith though, so please correct me if I'm wrong about that.