Friday, May 24, 2024

Biting The Silver Bullet: Increasing the Lethality of Ammunition

By Sanjay Soni

Sanjay Soni, MD Hughes Precision

If the role of the infantryman is to kill the enemy, how effective is he? 

The small arms doctrine defines maximum effective range as ”the greatest distance at which a weapon may be expected to fire accurately to inflict casualties or damage”. 

Interviews and open source reports from Afghanistan since 2001 reveal that soldiers are engaging the enemy at ranges from contact distance to beyond the maximum effective range of the M4 carbine. Since the adoption of the M16 rifle and its 5.56×45-mm cartridge, there has been instances of soldiers raising issues about the reliability of the weapon and the effectiveness of the cartridge as well. 

The infantryman’s ability to engage an enemy successfully is dependent on several factors. 

  • Optics: The capability of the soldier to see the target 
  • Tactical Marksmanship: The capability to hit the target 
  • Reliability: The capability of the weapon to function in the environment  
  • Mechanical Accuracy: The capability to deliver the bullet accurately to the target 
  • Cartridge Lethality: The capability of the bullet to incapacitate the enemy

The infantryman’s ability to fix or kill the enemy with organic weapon systems at distances beyond 200 meters is limited by his equipment and training. 

The maximum effective range of the M4 carbine is incorrectly listed as 500 meters for a point target and 600 meters for an area target. These ranges only take into account the ability of the weapon and ammunition to hit a target and not the terminal capability of the cartridge. 

For example, the M16A1 Garand and M14 rifles, firing a 150-grain bullet, and the M16A1 firing a 55-grain bullet, all have the same maximum effective range of 460 meters. Clearly, these ranges do not vector in the terminal ability of the round to inflict casualties. 

The M855 cartridge is effective to a distance of 200 meters after which its effectiveness is limited unless hitting a vital area of the target.

Bullet Fragmentation & Yaw

The incapacitation mechanism of small caliber bullets, such as the 5.56-mm, comes primarily from bullet fragmentation. The ability of a bullet to fragment is dependent on several factors, including overall design and construction, and more importantly the velocity at which it strikes the target. Spitzer shaped bullets will travel a certain distance within a target before exhibiting yaw. 

For a bullet to exhibit yaw, it must be somewhat unstable when it hits the target. Small caliber, high velocity rounds are especially dependent on this instability for their lethality. For the M855 cartridge, maximum stability is from 150 meters out to 350 meters and it is potentially less lethal between these two ranges.

If a bullet begins to yaw and its velocity remains high, the stresses on the bullet become too great and it breaks up into multiple fragments, typically at the cannelure.  As the bullet enters the body, the tissue expands away from the path of the bullet. This expansion creates a temporary wound cavity. In some cases, the tissue expands beyond its elastic limit and tears, creating a large, permanent cavity. 

Additionally, the fragments will move radially away from the path of the bullet and act synergistically with the stretch of the temporary cavity. This combined effect of stretch and fragmentation results in an overall increase in the size of the permanent wound cavity. The closer these effects occur to a vital organ, the more lethal the wound. 

A bullet which does not yaw will only create a small permanent cavity and most of its energy will not be deposited in the body, but will continue through the body resulting in a minor wound, generally of .22 caliber (5.56-mm) diameter.

Tests By Dr Martin L Fackler

Tests conducted by Dr Martin L Fackler at the U.S. Army’s Letterman Institute show a predictable pattern of fragmentation based on impact velocity. From these tests, it is clear that for reliable fragmentation effect, the velocity of a 5.56-mm bullet must be above 2,500 feet per second when it impacts. Translating this velocity threshold to a range indicates that the target must be within 200 meters if the round is to break into at least two fragments.

Pattern of fragmentation: Dr Martin L Fackler’s Test Results

Dr. Fackler’s tests concluded that 70 percent of the time a 5.56-mm bullet travels 4.7 inches in tissue before yawing. Fifteen percent of the time, it would yaw after this distance and 15 percent of the time, it would yaw before 4.7 inches. It is clear that 85 percent of the time,  the bullet will not begin to yaw and fragment until it penetrates almost five inches of tissue – even within the velocity threshold of the 5.56-mm cartridge, the bullet will not begin to yaw and fragment until it penetrates almost five inches of tissue. With small statured or malnourished enemy combatants, the majority of bullets will just pass through the body unless the bullet strikes bone or enters at an oblique angle.

One notable incident occurred in 1991, when then Lieutenant Colonel David H. Petraeus was shot in the chest by an M855 round from an M249 squad automatic weapon. He walked out of the hospital several days after the accident. Had the round performed optimally, likely he would have been killed. 

In another incident, a soldier shot in the shoulder from a distance of 75 meters during a night live fire exercise was walking around smoking a cigarette twenty minutes after the accident!

How Do We Improve The Lethality Of The 5.56x45mm Ammunition?

Elbit Systems 5.56mm APM performance

There have been advancements in the area of improving lethality of the 5.56x45mm ammunition.

The 5.56 APM Performance features a highly compacted WC front core in addition to the standard lead core. This offers much better performance in terms of lethality as well as accuracy (refer above table). It obviates the need to carry a heavier caliber weapon like a 7.62mm chambered rifle to achieve higher kill ratios over long distances.

Enhanced Penetration Bullet

The Russians have also come out with an “Enhanced Penetration Bullet” for the 5.56x45mm and the 7.62x39mm rounds.

The enhanced 5.56x45mm cartridge can penetrate a 16mm thick steel plate at a distance of 100 meters. Most probably they are using a tungsten insert to achieve enhanced penetration capabilities.

Some manufacturers use Tungsten inserts or Tungsten powder inside the bullets to achieve higher lethality. Others use frangible or Jacketed Hollow Points. However, these make the ammunition very expensive. That’s why they are mainly used by specialized commando units or special forces in operations where additional lethality is required to suppress or overcome the enemy.

In the 7.62x39mm caliber, the Russians have developed an Armor Piercing bullet which can pierce an Armor Slab 2P, 5mm at a distance of 200 meters. This is much higher penetration than the standard steel core bullet which is normally used in the 7.62x39mm cartridges.

The regular steel core cartridge is depicted on the left, with the Armor Piercing cartridge depicted on the right.

Improving Marksmanship

In the 7.62x39mm caliber, the Russians have developed an Armor Piercing bullet which can pierce an Armor Slab 2P, 5mm at a distance of 200 meters. This is much higher penetration than
the standard steel core bullet
which is normally used in the
7.62x39mm cartridges.

Ironically, it has been proven that the best way to improve the lethality of a fired cartridge is by improving the marksmanship of the soldier. 

The regular steel core cartridge
is depicted on the left, with the
Armor Piercing cartridge
depicted on the right.

The current marksmanship qualification course does not accurately depict the enemy on the battlefield.

It is based on the 1960’s and 70’s concept of active defense strategy. Targets come up and depending on their range, remain up for 5 to 10 seconds. 

The modern battlefield is never this static.

Soldiers fire 20 rounds from a foxhole supported position, then ten rounds from a prone unsupported position and finally ten rounds from the kneeling position. Soldiers are conditioned to expect that their targets will not move, will require only one shot to incapacitate, and a hit anywhere will result in that incapacitation.

Ideally, an updated qualification course will have the following characteristics:

  • Engagements from 3 to 500 meters; include multiple types of terrain requiring different shooting positions
  • A combination of moving and stationary targets
  • Engagements from differing elevations 
  • A scoring system which rewards shot placement to vital areas

The Three Training Elements

Terrain and position shooting can be accomplished with updated known distance ranges, while the current qualification range can add moving targets and towers for elevation shooting. Finally, a short-range marksmanship course can be added in maintain close quarters battle capability. 

These three elements should be combined to give an overall score for classification as an Expert, Sharpshooter or Marksman. 

The optimal incapacitation window for 5.56-mm is within 200 meters and beyond that only accurate shot placement will likely result in incapacitation. 

The modern infantryman is burdened with excessive weight in the form of protective gear, communications equipment, and weapons systems. He is fighting an enemy conditioned to the elevation and terrain. The enemy travels light and employs standoff supporting weapons, including mortars and medium machine guns. 

Faced with these conditions, the modern infantry attempts to fix the enemy with direct fire and supporting assets. Under these circumstances, the need for the precise application of direct fire is more important than ever before. 

However, the ability of the infantryman to deliver precise fire that incapacitates targets beyond 200 meters is limited by current equipment, training and doctrine. That needs to change.

Sanjay Soni is the Managing Director of Hughes Precision Manufacturing Pvt. Ltd., India’s first small calibre manufacturer in the private sector. An MBA from the Indian Institute of Management, Bangalore, he has been involved with the ammunition industry in India and abroad since the last 8 years.


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