Yeah, it gets tricky bexause when you fill the depression some of the finish builds up outside that spot. Once you get the place filled in, then work up through the Micromesh grits. I start with the 1500 just around the original spot, to reduce the built-up edges. With each successive grit I sand a larger area, by the 12000 I am sanding the entire barrel - that eases the trasition and blends the finish, hiding the original spot.
It doesn't take long to work up through the grits 10-20 seconds per grit, the 1500 may take a bit longer.
Chris