Vietnam era M-1 C

Another Vietnam era US M-1 C that I recently added to my collection there is a lot going on with this example such as it would appear to be a depot retro-fitted and re-baled WW II McCord FS FB that shows good strong dimple marks in between the bails on the rim if I am reading the heat stamp correctly it is (215 B )
This particular helm has a nice used look about it and shows the expected patina stain and wear to the interior furniture and the helmet body one would expect to see on a period used lid as best I can tell the sweat band is dated to 1972 it is impossible to make out the date on the suspension on the liner I am afraid it is far to gone .
I believe the contract number on the Mitchell puts the production in 1969 if I understand the DSA correctly thanks for looking all comments are most welcome.

Regards Mark