There should be an NSN on the QR code on the magwell, but since you only have the upper... (poor reading comprehension on my part)
The M4A1 is 1005-01-382-0953
The M4 is 1005-01-231-0973
Another obvious difference would be that the M4 is burst while the M4A1 is full auto. Both should have KAC rails, but the M4A1 has a thicker barrel profile especially under the handguards. The barrel is the best way to tell from what you have.
Last edited by Eurodriver; 10-30-14 at 14:25.
Why do the loudest do the least?
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