Going back to WW2 some how a myth got started that if you buckled your chin strap and an explosion went off close to you, the concussion would be caught under the helmet and like a parachute, it would catch it and break your neck or rip your head off. This myth last at least till the Vietnam war when my Dad heard it and believed it.. You can still see it referenced in media now. The Pacific had a moment when Sledge nearly gets his neck broken during his first beach landing.
Of course if you are close enough to a blast to have it cause the helmet to break your neck then you have much larger problems.
The myth became so widespread that the Army even developed a second model chin strap for the M1 helmet.
The first version used this hook system. Very simple and strong. But the rumor took over..
So the Army came out with this second version with a ball that would break apart if 15 pounds or more of force was exerted on it.
Probably a good idea anyway.
Oddly no one thought it mattered when it came to the Airborne liner and system that used two chin straps and a yoke.
Scattered Shots 
I spent ten years training for close range tropical jungle warfare (think Papua New Guinea, Borneo, Malaysia, Vietnam), and all I can say is that anybody wearing one of those things in a jungle fight is at a major disadvantage.
They’d be useful in trench warfare where there’s significant risk from overhead shrapnel bursts, but in the jungle they’re heavy, hot, uncomfortable and reduce your situational awareness enough to get you killed pretty quick.
You need something to break up the outline of your head, and from which you can hang shrubbery or scrim, but a tin pot ain’t it, at least in my neck of the woods.
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Years ago I mentioned nearly the same thoughts about a helmet in the jungle to my Dad and he said when he was in Vietnam and the NVA was dropping 82 mm mortars on their position is was damned glad he had that helmet. As bad as it must have been to wear a helmet in Vietnam, the psychological benefit of having it while under fire can not be discounted
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