Hey do any of you guys know where I can easily look up the serial # of my M&P AR15 and learn specifics about when it was made? I bought it used (spotless) so I don't have any idea how old it is or if there's anything to look out for from its production run. It's an 811000/ 16"/ removable grab handle/ 5.56-.223/ 1X9" barrel. Thanks!