Like a lot of people, when I got my 82 the paint on the sights was almost completely gone, so before I took it out I put some white enamel in the dots on the rear sight, and filled the notch in the front sight like I'd seen suggested here and on other boards. Visibility ++.
Then when I shot it I found (sound familiar?) that I was shooting low. Then I realized what I was doing wrong - I was borking up the sight alignment by unconciously trying to equalize the amount of white I was seeing on the front and rear sights. What I mean is the rear sight dots are only so big, but on the front sight I had painted a long strip of white and since my natural instinct was to assume that I should be seeing 3 equal sized dots of white side by side, I was holding tilted down to "hide" more of the stripe.
Once I started ignoring the paint and focusing on the iron it brought my POI up nicely. Since then I've started to scrape away some of the paint on the front sight, but I haven't got it quite right yet. Still I'm glad I've only got to mess with the paint, instead of file away any metal.
Might not be the issue for most of the people who're hitting low, but maybe it can help some. Check your sight picture!
C.C.