I would use a block and 400-600 grit sandpaper, instead. Sure, sure, it will leave micro scratches...believe me, the manufacturing process didn't leave something like the surface of an optical mirror, say with an RMS error of 1/4 wave.
When it comes to doing your turnouts with the block, so that you don't pick the points and bend them, use the sanding block from the frog toward the points.
Finally, if you want to get fancy, run a washer over your rail surfaces, back and forth, and polish them to a much finer surface. You won't be disappointed. Careful near those points!
