I just picked this up off the EE here. The seller said it was a COLT 10.5" upper. But I never seen a Colt 9mm barrel marked with " 9MM-NATO" between the FSB legs. So looking a little closer I see a "C" on top on the barrel right under the FSB. And part of the "M" under the front leg of the FSB. So I had see if the rest of it was there under the front leg. So I removed the FSB and there was the rest of the normal Colt Stampings.

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While I have never owned a short barrel 9mm, it does look OK to me.
My guess is that Colt did that so they could get it all to fit on the short barrel.

Doesn't look like any real Colt barrel I've ever seen. All the factory 10.5" 9mm barrels I have seen have been marked under the handguards.

After some looking around I found another Colt barrel marked the same way that sold on ARMSLIST awhile back. It was also an 10.5" 9mm barrel.