Depeeka Greek helmet

[Gaius Julius Caesar]

The Deepeeka 'Italo-Corinthian' is, as Matt Amt says, quite a reasonable reproduction of an early 5 C BC Corinthian helmet found at Olympia. Nor is it "too thin".......
Late Corinthians,being individually made, varied in thickness from helmet to helmet, and each helmet varied in thickness in different parts, like modern tank armour, being thickest where most vulnerable. An average of 0.75-1.25 mm is about right...this equates to 18(1.03 mm) or even 20(0.81 mm) gauge sheet brass, and this is what almost all repros are made of......the Deepeeka helmet is 18 gauge. It's weight is about right too, and it's only real flaw, in common with most modern repro's, is that it is of uniform thickness all over......

As to 'yellow' or 'red' brass....see attached well-preserved example.....

Well, sorry to disagree with the 'not too thin' statement, perhaps they have changed them since the one I handled was made, but it was nowhere near 18 guage......the nasal was paper thing, and, as you correctly say, the rest of the helmet was of uniform thickness, which is totally incorrect.
While the helmets did vary in thickness, I am certain none were as thin as the one I saw. If they have made changes since though, then that is a step in the right direction.