I just bought two new Colt bolt carrier assemblies from a vendor.
The part (breech bolt assembly) arrived with a NSN part No.1005-01-442-3770 on the package vendor label (and no mention of Colt). The parts seem new and are wrapped in a sealed plastic bag.
From searching on the internet, I found that in 2008 the NSN number became 1005-01-505-1035. I guess the extractor assembly was also changed (from 5360-01-424-5899 to 5360-01-505-2886) so the M16 and M4 could use the same bolt carrier assembly.
What did I get - is it OK? How do I know it is Colt?
Thanks

C     is stamped   into  the carrier