colt 6920 barrel extension mark/marring

[jimbob2525]

what's this square/diamond imprint here on the barrel extension? just a blem and doesn't matter? bought this as a new 6920 takeoff.

4575945760

[M Sadler]

The "4" indicates carbine extension and is correct. I'm not sure about the diamond other than its there to cover what maybe looks like a 3 under it.

[davidjinks]

I believe it's a over-stamp to mark out an incorrect marking.