A modernized steel helmet is simultaneously lighter than the PASGT and performs better against both fragments and handgun rounds

Thursday, May 25th, 2023

The first modern combat helmet was the French casque Adrian which was designed to address the threats soldiers faced in the Great War:

In WWI, explosive or fragmenting munitions were responsible for roughly 60-70% of all combat casualties. At the battle of Verdun, fragmentation and shrapnel from artillery bombardment caused at least 70% of the approximately 800,000 casualties that both sides suffered. The remainder were, for the most part, inflicted by relatively heavy rifle and machine-gun rounds which even the best helmets of today would not be able to stop.


The first helmet of the war to enter mass production and see widespread use — and the first modern combat helmet — was the French casque Adrian. This was made of mild steel, 0.7 to 0.8mm thick, with a tensile strength of at least 415 MPa and moderate ductility. (18% tensile elongation.) This helmet was capable of resisting a 230-grain, .45 caliber ball round at 400-450 feet per second, which is roughly half the .45 ACP’s muzzle velocity. But notwithstanding this poor performance against bullets, it is estimated to have defeated 75% of all shrapnel impacts from airburst munitions, and it had, therefore, an immediate positive impact on troop casualty rates and morale. In the Adrian’s wake, every other participant in WWI — except for Russia — hastened to develop and issue steel helmets of their own. Like the Adrian, these helmets had very poor resistance to small arms impacts, but were highly effective at protecting their wearers from shrapnel and fragmentation.

These same steel helmets, with minor modifications in some instances, were employed by all American and European forces through WWII. And here they proved even more vital, for whereas fragments and shrapnel accounted for approximately 65% of all WWI casualties, they accounted for 73% of WWII’s wartime wounds. The widespread use of the steel helmet shifted patterns of wounding and was highly effective at preventing fatal head injury. When the war was over, it was calculated that of all hits upon the US military’s M1 helmet 54% were defeated and, in fact, of all incapacitating hits upon the body, the M1 helmet prevented 10% of them.

Needless to say, all of the helmets of the war were totally incapable of stopping 8mm Mauser, 7.62x54mmR, or .30-06 bullets at most engagement distances — and in fact they would, invariably, fail to stop 7.62x25mm Tokarev handgun/submachinegun rounds within 100 yards under normal ballistic test conditions — but that wasn’t their intended function.


Interestingly, the soft, large, and extremely heavy .45 ball ammo that was used as the test projectile for the M1 couldn’t possibly have been more different from the fragment-simulating projectiles (FSP) used to test helmets today. The FSPs are much lighter — ranging from 2 to 64 grains — and they’re made entirely of AISI 4340 steel heat-treated to 30 HRC. With no jacket, no deformable lead core, and much lighter weights and lower diameters, they’re a qualitatively different threat in every respect.


In the mid 1960s, duPont chemists working on materials for automobile tire reinforcement identified a high-modulus polymer fiber which was first named PRD-49-IV was later trademarked and sold as Kevlar® 29. This material was of immediate interest to the US military. For at the time of its production it was 2.5 times as strong as any other textile fiber, and its performance was 60-100% better than ballistic nylon on a weight basis. Little time was wasted in replacing the nylon and fiberglass flak jackets with more protective and lighter Kevlar vests. And, taking a page from the Hayes-Stewart, Kevlar-laminate helmets — stiffened with about 20% by weight of a polymeric (PVB-phenolic) resin — were developed. Both the vests and the helmets were introduced as the PASGT program, and were issued to the troops in 1983. Some U.S. soldiers wore PASGT helmets in Grenada (Operation Urgent Fury) in 1983, Panama (Operation Just Cause) in 1989, and in the Middle East (Desert Shield/Desert Storm) in 1990-1991.


The PASGT, though not officially rated to stop handgun rounds, was also demonstrably capable of stopping 9mm FMJ service ammunition at typical muzzle velocities.

All of this is tempered somewhat by the fact that the PASGT helmet is markedly heavier than the M1. A size XL PASGT weighs 4.2 pounds; a size XL M1 weighs 2.85 pounds. (The M1 was only offered in one size, which corresponds to an XL in dimensions and coverage.) Were the M1 made 47% heavier, thicker, out of a more modern steel alloy, it stands to reason that its protective capabilities could have kept pace, at a much lower cost and with superior performance against small-arms projectiles. Indeed, we know that this is the case, for a modernized steel helmet — the Adept NovaSteel — is simultaneously lighter than the PASGT and performs better against both fragments and handgun rounds. It is frankly surprising that something along such lines was never attempted or, seemingly, considered. As things stand, it could be argued, and very convincingly, that the introduction of the Kevlar helmet was a mistake.

And that’s without taking into consideration the fact that the PASGT was perhaps an order of magnitude more expensive than the M1, which cost the military $3.03/unit in the early 1950s. ($1.05 for the manganese steel shell, $1.98 for the liner.)

While ballistic protection provided by helmets has increased significantly since WWI, blast protection has not.


  1. Pseudo-Chrysostom says:

    The myth of progress needs to justify itself, and that means constantly changing things, regardless how it changes for the worse, or the opportunity costs of upending something in of itself, irrespective of utility.

    In terms of blast protection, there are interesting possibilities with regards to expansive fabrics (woven in such a way that volume increases when stretched, like a box unfolding).

  2. Beans says:

    The next great change in head survivability was with the introduction of reactive foam linings, like D3O and similar materials.

    Team Wendy (yes, a real company) created a reactive foam helmet lining/helmet suspension system that radically reduced chances of traumatic brain injuries and offers more comfortable support in the typical kevlar helmet.

  3. Isegoria says:

    When I went to look up D3O, I realized I’d mentioned it here before:

    As keen snowboarders, Palmer and Green drew inspiration from snow and decided to replicate its matrix-like quality to develop a flexible material that incorporated the dilatant fluid. After experimenting with numerous materials and formulas, they invented a flexible, pliable material that locked together and solidified in the event of a collision.

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