Nunbers inside M1917 Doughboy Helmet Dome

[M16Man]

Hello all, I'm happy to have just joined this forum. I just bought my first WW1 piece the other day: this beautiful M1917 Doughboy helmet with the 77th Liberty Division insignia on it! I noticed that there are some numbers on the inside of the dome under where the liner would've been. It reads "24533". Has anybody seen this before on any doughboy's? It doesnt have the liner or straps. The heat stamp says ZF41. Any info would be a great help. Thank you!

[M16Man]

[aef1917]

Raising this one from the dead.

 

Despite frequently being called "heat numbers" by collectors, the brim markings on these, they are actually manufacturer/lot codes, and can only be tied back to the actual heat number using the Ordnance Department's master lists.  Here we can see that lot 41 corresponds to the stenciled 24533 heat number.