So, this is interesting. Yesterday, Portfolio's Jeff Bercovici said Times reporter David Carr's memoir The Night of the Gun hit No. 21 on the Times' own best-seller list for hardcover non-fiction list, "right after Freakonomics and just ahead of Southern Storm." Sound impressive? Maybe not. One source who looks these sort of things up on Nielsen BookScan reports Carr's book has moved only 3,342 copies since it went on sale Aug. 5. Yesterday, Carr's book was down to No. 71 on Amazon.com's best-seller list; today it's slipped again, to No. 82.