Soldiers and Marines have long debated the value of chin straps, most likely in extreme conditions. After rigorously testing thousands of helmets, X Shell is 100% positive that a tight chin strap actually INCREASES MTBI risk from ballistic events on X Shell helmets. X Shell’s tests measured backface deformation in ROMA Plastilina clay to quantify the trauma transferred to a soldier’s head during a ballistic loading events only.
X Shell has concluded that a strapped-down helmet hurts the soldier in two ways. First, more energy is transferred to the clay than if the same helmet is allowed room to move, and the second is rotary injury. If a helmet can rotate without rotating the head with it, energy can bleed off and protect the solider from injury to the brain and neck.
The proper way to wear a helmet is to use a ratchet dial to get a snug fit on the head and then loosely allow the chin strap to hang below your chin; this is simply to keep the helmet on your head. Only during the use of night vision is a tight chin strap required.
This is internal data and is completely based on ballistic transfer of energy to X Shell Helmets only. In the event of blunt force impacts, chinstraps are recommended and they do save lives.