While looking at something else on a posting a while back I came across this:
http://www.americanrifleman.org/ArticlePage.aspx?id=2259&cid=4
This applies to several guns that make the claim they are “MilSpec” simply put if it’s not government surplus or stolen it’s not a “Spec” gun anymore than any other gun made.
For one thing an AR has a different pattern to the way the interior of the lower receiver is milled than a M4 or M16 and they don’t have all the holes drilled to hold the additional parts in an automatic weapon.
Should Note that DaveM’s Bowie might be a Spec knif