Jerry is quite correct - I've never seen two original barrels milled (er, filed) the same. I think crisp sharp flats may be a bit much, and usually knock them off with a couple light strokes of a file. When taking original barrels out of the stock, I've found some barrels filed pretty crisp, and others with edges knocked off, still more with completely round bottoms (and octagonal top half). The rest is your personal preference.
-Eric