Have posted before... little snippet from the article below.
American Rifleman | The MilSpec Definition


"Now if anyone has a vested interest in making you believe that their ARs are MilSpec, it would be Colt...

Yet Colt is the first to admit that their commercial ARs are not MilSpec! I submit to you, ladies and gentlemen of the jury, that you now have your second and final piece of conclusive evidence that there is no such thing as a MilSpec AR."