"Mil-Spec" is such a misnomer in the wide wonderful world or M16 type rifles.
NO civilian semi auto AR rifle will EVER be truely "MIL-SPEC" simply because there is so much difference in the fire control group.
Fact is, in many examples, the current civilian production parts and accessories for M16 type rifles will actually EXCEED the standards set down as military specification.
ETA; Barrels are an example of better than Mil-Spec, so are things like Magpul grips, Tango down grips, available back up iron sights, stocking options, bolts, bolt carriers, springs, free floating forends, gas blocks,,,,the list can go on.