OK. MY Colt AR15A3 Tactical carbine is as follows:

Marked Colt AR15A3 on the lower receiver. Below that is
SN BD002915 (only thing I can find is this/ BD000134 and Below - Pre-Ban (AR-15A3 Tactical Carbine - very rare model).

On the barrel is marked CMP (I THINK) and 5.56 Nato 1/9 Hbar.

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