I have my son's (deceased 12/8/08) M&P-15T that has what seems to be a very low serial #: 00006XX. With the large numbers produced, I doubt if there is any value in the low number, even with the original case and packaging. Wouldn't sell it anyway. He loved this gun and it has been accurate, reliable and has all his add-ons (original parts saved too). My question: Have there been any real changes since those early guns? Were the early M&P 15s made by S&W or were they sub-contracted? I know this is the place for the facts. Any information would be appreciated.