My post was meant to support your statement not to question it
Good article published by the US Army Medical Department:
On the WW2 US M1
"Some aspects of the value of the M1 helmet are discussed by Beebe and DeBakey in their book on battle casualties.4More recently, Norman Hitchman5 of the Army's Operations Research Office reviewed some of the World War II casualty statistics and reached some important and timely conclusions regarding the value of wearing a helmet in combat. The following observations resulted from this statistical analysis:
1. Of all hits upon the helmet, 54 percent were defeated.
2. For every 100 men wounded while wearing helmets, 9.6 men received wounds in the cranium. Without the helmet, it would be expected that 11.4 men would be wounded in the head.
3. The M1 helmet prevented a number of incapacitating hits equal to 10 percent of the total hits on the body.
4Beebe, Gilbert W., and DeBakey, Michael F.: Battle Casualties. Springfield: Charles C. Thomas, 1952, p. 176. 5Hitchman, N. A.: Keep Your Head . . . Keep Your Helmet. Army 8:42-44, September 1957.
4. The estimated savings in total battle casualties means that the helmet in World War II probably prevented wounds in more than 70,000 men. A significant proportion of these men would have been killed had the helmet not been worn.
5. To get the same amount of saving by protecting other regions, body armor weighing more than twice as much as the helmet would have to be provided."
- Should be also obvious that the main purpose of a helmet was not to protect from direct good-angle impact penetration by rifle rounds or them to do wonders. "However, battle casualty survey studies during World Wars I and II and the Korean War have shown that the primary wounding agent among the WIA and the KIA casualties was the fragmentation-type weapon"
- that helmets cover a small part of the body is evident but it should be obvious that the upper cranium is one of the most critical areas when it comes to incapacitation and/or death. It is also a good idea to think outside of a wargamer chair as everybody with a service record would point this out: what is a more-than-usual exposed body part when situated in a trench, foxhole or in a typical (prone) firing position? Exactly. Thus simply comparing helmet body % vs overall body % is lacking.
- For the French Adrian helmet 60-70% reduction in shrapnel head injury are thrown around in articles. These are secondary/tertiary sources and I never saw the primary source so I am in doubt about this high numbers without sighting the ps, could be "Helmets and Body Armor in Modern Warfare" by Dean, Bashford (1920) but not confirmed. The soldiers were often subject to shrapnel projectiles coming from above, these numbers could be very situational.
- it was stated in this thread that the true protection of WW2 steel helmets is in the dark and that is exactly the case and what a good researcher/expert would point out.
- Being almost a decade involved with military professionals, studying at military schools, reading multiple, multilingual sources, witnessing shrapnel/fragmentation and the protection of similar fashioned gear first hand I can´t remember coming across an opinion stating WW2 helmet shrapnel protection did not matter too much as it would be self-evident.
Despite this it is not a really important discussion for me as I am currently fine with how the CM simulation behaves when it comes to frag/shrapnel and that headgear is to some extent incorporated is a fine extra.