Are Combat Helmets Bulletproof GTA?
Ballistic protection rating of bulletproof helmets
Modern ballistic helmets offer varying degrees of protection. These levels are usually tested according to the National Institute of Justice. The NIJ evaluates ballistic protection based on the ballistics that proved the item was able to stop during rigorous testing. Tiers III and IV will stop regular rifle rounds. Classes I to IIIA are rated to stop all kinds of pistol rounds, with class IIIA stopping pistol rounds including .44 magnums. While other ammo is not always tested, there is an assumption that a ballistic helmet that can stop 0.44 magnum ammo will also prevent 0.25 auto ammo or some other rental power ammo.
20th century steel helmets have poor resistance to small arms threats, PASGT, MICH, FAST, ACH and most class IIIA helmets will stop almost all pistol caliber threats, but will not stop rifle bullets, ECH and IHPS will stop some rifles Threats, but cannot reliably stop all or even greater threats, and helmet shell deformation can cause the shell to come into contact with the wearer's head, potentially causing serious injury; future helmets will reliably stop steel core rifles with minimal helmet shell deformation ball threat.
The earliest steel helmets developed in the 1990s to protect against indirect fire, such as mortar shell fragments, were not officially rated to stop any pistol or rifle bullets.
PASGT is the earliest aramid helmet, which can effectively block fragments and shrapnel, but cannot prevent the threat of small arms, but aramid helmets such as PASGT, MICH, FAST can block pistol ammunition, such as: 9*19mmFMJ.
The ACH helmet is an improved aramid helmet based on the PASGT, discarding design flaws discovered over the years to defend against more lethal, higher, or greater mass threats than the 9mm FMJ RM.
Combat helmets were developed as a military tool. Military planners were well aware that indirect fire from mortars and artillery would inflict horrific casualties, so the first helmets were designed and released to deal with these particular threats. The first helmet of war to enter mass production and become widely used - and the first modern combat helmet - was the French casque Adrian. It was made of mild steel 0.7 to 0.8 mm thick and had a tensile strength of at least 415 MPa, moderate ductility. (18% tensile elongation.) This helmet can resist a 230-grain, 0.45 caliber projectile at 400-450 feet per second, which is about half the muzzle velocity of 0.45 ACP. However, despite its poor performance against bullets, it is estimated to have defeated 75% of the shrapnel impact from air-explosive ordnance, so it has an immediate positive effect on troop casualty rates and morale. After Adrian, all the other players in World War I - except Russia - rushed to develop and issue their own helmets. Like Adrian, these helmets have poor resistance to small arms impact, but are very effective at protecting the wearer from shrapnel and debris.
These same steel helmets, in some cases slightly modified, were used by all American and European armies during World War II. Here, they proved even more important, as debris and shrapnel accounted for about 65 percent of all casualties in World War I, but they accounted for 73 percent of wartime injuries in World War II. The widespread use of steel helmets has changed injury patterns and has been very effective in preventing fatal head injuries. After the war, it was calculated that 54% of all hits by the U.S. military M1 helmet were repelled, when in fact, the M1 helmet prevented 10% of all mutilating hits to the body.
Needless to say, all helmets in war are completely incapable of stopping 8mm Mauser, 7.62x54mmR or .30-06 bullets at most engagement distances - in fact, they will never stop a 7.62x25mm Tokarev pistol/submachine gun under normal ballistic test conditions down, firing at 100 yards - but that's not their intended function.
So it's interesting that these helmets are often tested against bottom-loaded pistol cartridges for quality control purposes. [4] While the helmet is designed to destroy fragments and shrapnel, it is impractical to simulate projectiles with fragments alone. Simulating fragments and shrapnel was a difficult problem requiring specialized test projectiles, and no suitable methods had been developed at the time.
The M1 is typically tested against 0.45 caliber projectiles. It has a ballistic limit of 230 grams. A 0.45 caliber projectile with a gold-plated metal casing and soft lead core has a velocity of 761 to 911 feet per second, with the caveat that the front of the M1 helmet should reliably stop such bullets at 35 yards.
The M1 helmet targets 230 grain .45 caliber marble ammunition with a copper clad steel jacket and "hard" lead core, with significantly reduced performance, so ballistics are limited to between 542 and 735 feet per second, depending on impact location and other factor.
124 grams. 9mm FMJ ammunition with a muzzle velocity of 1250 feet per second, the M1 was reliably penetrated to 130 yards and beyond. The range of tests used by the military at the time was not expanded further. [5]
Interestingly, the soft, large, and extremely heavy 0.45 projectile used as the M1 test round is not too different from the Fragmentation Simulated Projectile (FSP) used to test helmets today. FSPs are lighter - ranging from 2 to 64 grains - they are made entirely of AISI 4340 steel heat treated to 30 HRC. With no sheath, no deformable lead core, lighter weight, and smaller diameter, they are a different threat in every way.
Regardless, despite being objectively poor at countering the pistol threat, the M1 helmet has been standard equipment for American soldiers for decades. It remained in service until the early 1980s, and is by and large the longest-serving U.S. military helmet. But serious efforts to replace it with an improved helmet began in the 1960s and continued into the 1970s.
At first, different bulk materials such as titanium and polycarbonate were considered and hundreds of prototypes were made. Titanium helmets were deemed too expensive—they performed better than the extremely cheap M1, but were not considered a significant enough improvement. Polycarbonate helmets, while relatively impressive in terms of performance, were removed from the competition due to their poor resistance to solvent and chemical exposure. Ultimately, these and many others did not yield any helmet material that could potentially replace the M1 WWI vintage Hadfield steel. (By the way, many of these efforts—including the polycarbonate helmet—were carried out under the LINCLOE project, which culminated in the ALICE gear system.)
Fiberglass helmets were also prototyped and checked, and while they showed better ballistic performance compared to the M1 helmets, they lacked durability and were prone to delamination in salt water. They were not adopted by the U.S. military, but the first ballistic police helmets were made of fiberglass and modeled on these early U.S. military experiments.
In the mid-1960s, DuPont chemists researching automotive tire reinforcements discovered a high-modulus polymer fiber originally named PRD-49-IV, later registered and sold as Kevlar® 29. Interested in the U.S. military. Because at the time of its production, it is 2.5 times stronger than any other textile fiber and performs 60-100% better (by weight) than ballistic nylon. Replacing nylon and fiberglass body armor with more protective and lighter Kevlar vests is almost no time wasted. And, drawing on Hayes-Stuart's experience, a Kevlar laminate helmet was developed - reinforced with about 20% by weight polymeric (PVB phenolic) resin. Both vests and helmets were introduced as part of the PASGT program and issued to troops in 1983. Some US soldiers in Grenada in 1983 (Operation Urgent Rage), Panama in 1989 (Operation Just Cause), and the Middle East in 1990-1991 (Desert Shield/Desert Storm).
Unlike the M1, the PASGT helmet was tested against a true FSP and was tested against 17gr with the V50. The .22 caliber FSP showed better performance than the M1 at 2000 feet per second, the V50 of the M1 was about 1000 fps. [6] PASGT outperformed M1 by 42-79% over the entire FSP range from 2 to 64 grains. [3] The PASGT, while not officially rated as a stop pistol bullet, has also been shown to stop 9mm FMJ service ammunition at typical muzzle velocities.
Unlike the M1, the PASGT helmet was tested against a true FSP and was tested against 17gr with the V50. The .22 caliber FSP showed better performance than the M1 at 2000 feet per second, the V50 of the M1 was about 1000 fps. [6] PASGT outperformed M1 by 42-79% over the entire FSP range from 2 to 64 grains. [3] The PASGT, while not officially rated as a stop pistol bullet, has also been shown to stop 9mm FMJ service ammunition at typical muzzle velocities.
All this is tempered by the fact that the PASGT helmet is significantly heavier than the M1. Size XL PASGT weighs 4.2 lbs; size XL M1 weighs 2.85 lbs. (The M1 is only available in one size, which corresponds to the XL in size and coverage.) If the M1 is made from a more modern steel alloy 47% heavier and thicker, its protective abilities can remain fast, cost-effective Much lower and has excellent performance against small arms projectiles. Indeed, we know this to be the case for a modern steel helmet -Adept NovaSteel - while being lighter than the PASGT and performing better against fragmentation and pistol rounds. Frankly, it's surprising that something like that has never been tried or never seems to have been considered. As things stand, it can be argued, and very convincingly, that the introduction of Kevlar helmets was a mistake.
Regardless, the PASGT helmet was adopted and was generally well received. There have been complaints about its shape, a helmet with a brim resulting in significantly reduced field of view compared to a helmet without a brim, and there have been many complaints about its webbing system, which is both uncomfortable and exhibits extremely poor blunt impact performance.
The Modular Integrated Communications Helmet (MICH) is a PASGT spin-off project led by U.S. Special Operations Command to correct these deficiencies. It retains the aramid shell but removes the brim, slightly changes the overall geometry of the shell for better access to communications gear, and replaces the webbing with foam padding. MICH is also slightly lighter than PASGT – partly due to changes in its geometry and partly due to slight advances in aramid technology and composite processing methods that allow for lower volume fractions of resin. The MICH was extremely well received and, with some minor modifications, was adopted by the Army as the Advanced Combat Helmet (ACH) shortly after its introduction. The ACH became the Army's primary combat helmet in the mid-2000s.
Unlike PASGT, MICH and ACH are rated to deter handgun threats. As a condition of lot acceptance, the ACH specification requires helmets to stop at 124gr. 9mm FMJ, 1400+50 fps. Backward deformation is limited to 16 mm for the sides and crown, and 25.4 mm for the front and rear of the helmet. ACH performs 10% better on fragmentation than PASGT, with a minimum of 17gr. FSP V50 at 2200 feet per second.
More recently, UHMWPE has replaced aramid as the helmet material of choice, and helmets made from this material are more resistant to penetration by debris and small arms threats - including rifle threats with lead or mild steel cores
