There is a lot of old info, hearsay, and just plain wrong crap that gets foisted off on shooters in the name of "da rulez"

When some "X-spurt" tells you X or Y "isn't legal" ask them to point to the applicable chapter and verse in the rulebook.

If they can't then they're FOS and you're free to ignore them.

FWIW, blacking sights (ie, changing their color) along with painting witness and other marks on competition rifles (sights, gas cylinders, etc) have been done for years and are an accepted part of the game.

Maury