Are there extended feed ramps in the upper receiver - either M4 style or the earlier “extended carbine” ramps? I have a 733 upper from 1996 that has the M4 ramps and a “4” stamped on the front of the upper receiver, which seems to be a mark used to denote A2/C7 style uppers with M4 ramps.
If you have ramps, do they appear to have been cut pre- or post-anodizing? Ramps cut post-anodizing don’t *necessarily* mean it isn’t factory original, as a lot of 6520 “government carbines”, including mine, apparently had their ramps added post-anodizing, but it’s just another thing to check.
I’d also check the barrel date and see if that jives with the date Colt gave you for the lower.
If it is all original it could be some kind of special run for a specific agency contract. I mean Colt built a bunch of dissipators for the CHP at one point, and they would apparently do other special runs of somewhat unusual configurations here and there.
Determining who the original intended recipient was could be interesting. If it’s in its original factory condition and new old stock, who knows it could even have been a gun intended for some foreign LE contract that fell through line those SDN Mexico 6920s that were floating on gunbroker around a few years back. Buying fixed carry-handle Commandos in 2005 seems like the sort of thing some Latin American country would do.
