i think the old school of thought was that, 11.5" and up were good to go, while 10.5" and down could be "finicky".
there are a lot of manufacturers turning out good product now, and many people are having 0 problems with even "mid-grade" 7.5" uppers.
if you want a 10.5", pick up a LMT or Colt, and you'll be good to go. for a little bit more coin, grab a noveske.