Help identifying M1 heat stamp

[Paper]

A while ago, I bought an M1 frankenhelmet that came with a European SW liner, American made corked/sanded steel shell and a Woodland cover.
The problem is, I do not know the era my shell was made in.
Thankfully the heat stamp is visible, I have attached it below (I don't know why it's upside down, I tried to fix it):


1210H (The second "1" is not stamped in properly, so it looks like a stick )

After some research, I have discovered that helmets with stamps containing 1200 (or some other value in place of the two zeros) are late war WW2 McCord stamps.
That is a bit of a stretch in my opinion, since my helmet has a rear seam and a ball tongue on it's green chin strap, which were all introduced post war
I'm thinking this helmet might be 60s or 70s.


I would love to hear your answers, I am from southeastern Europe so I don't know much about American M1 helmet designations

Thank you for your time!

[MAP]

Moved to the correct forum.

[Paper]

thank you mr. moderation

[ruddersrangers44]

Late ww2 McCord around may 45 production,been repainted for post war use.