I have this helmet and I would like more information on it. Especially the heat number and the number "1 2 (or 3) 6" on the bottom side of the shell peak. After lots of research on Google it seems to be a McCord shell. If wanting photos, please request them.
This is what I found out:

September 1942 (according to McCord)

Shell:
~ fixed bails
~ front seam
~ Heat # 272 (letter not present/missing?)
~ 1 (2 or 3) 6 (on peak)?
~ OD #3?
~ does have some stress cracks
~ OD #7 dark green net (reproduction- I added)
~ L: 11” W: 9.5” D: 7”
~ McCord (I’m positive, No "S")
~ cork texture
~weight: 2.5 Ibs
~ Raised brass bar buckle & 2 prong hook
~ Olive Drab (OD) tank green paint

Liner
~ high pressure
~ Seaman Paper Company
~ Post War leather chin strap (New old stock-I added)
~ Sweat band- (reproduction-I added)
~ weave forms 3 V pattern
~ nape/neck strap, nickel- no ID?

Questions
~ More Info on: the heat number, letter missing?
~ more info on: numbers on peak?
~ McCord,Ingersoll, R.J. Stampings or Schlueter?
~ est. Time period?
~ leather chin strap: Is it correct for the time period you think it is?
~ neck strap info