I recently bought a Colt 10.5" 9mm upper. The receiver has the proper Colt markings, but there are not any Colt ID stampings on the barrel. I took off the hand guards and there was a date stamp 4-97. But no CMP or 9mm NATO markings like I have seen before. The upper is like new,has a chrome bore, does not look to be refinished or a parts upper. (This was sold to me as all Colt, like new) Just wondering if this is normal. Any feedback would be
appreciated.

The 4-97 does not ring a bell, but the Colt SMG barrels are marked under the hand guards that I understand, could be a 16" that was cut down... then the markings were lost, as they were forward of the sight base.

Unscrew the barrel nut, and see if the flange is thin like quarterbores in this thread >>>> 9mm Colt barrel on the left (thinner flange, uses a washer at barrel nut)
[url]http://www.ar15.com/forums/topic.html?b=3&f=15&t=175508[/url]

[img]http://quarterbore.com/images/barrelflange.jpg[/img]