Colt 1911A1 Commercial/Military barrel question

I have a Colt 1911A1 Commercial/Military pistol SN-864,xxx. Slide and frame have matching serial numbers. The barrel has a .45 AUTO 7791193 on top and MP and MA on the lug. I read somewhere that some of these pistols were shipped with National Match barrels. After reviewing a number of these pistols on forums and auction sites, all had S or G barrels. Not knowing how a commercial National Match barrel is marked, my question; is this an original or replaced barrel.
I would appreciate any info you can provide. Thank you.

Your barrel is a replacement.
7791193 = GI chrome lined.
NM = 7791414 or 7791469 if packed with a fitted NM bushing.