So, instead of getting hit by a slug, the earth was struck by buckshot in a tight pattern. Would that explain the lack of metallic residue at the site? Pieces bounced off every which way?
There is not a "lack" of "metallic residue", just less than would be produced by a single large meteoritic impact, and of a different type than would be produced by a faster impact.
There's still plenty of iron from the meteor all over the place, though -- the plain around the crater is littered with it and people have been collecting pieces for over a century, but there's still a lot left.