Thursday, August 13, 2015

Big Bullets and Terminal Ballistics

A few days ago, I pointed my 6 or 7 regular readers to an article by Nathaniel Fitch at The Firearms Blog about the performance (basically, the downsides) of traditional blackpowder firearms over those using modern powders, as well as some discussion of the benefits of modern bullet manufacturing over just throwing out a straight lead slug.

Fitch's article observes that the biggest downside of blackpowder from a ballistics standpoint is that it is less energetic than modern smokeless powders. Thus, most loads and weapons generate much lower velocities than modern projectiles, so that "in general, a blackpowder weapon will have to be larger and fire larger cartridges (whether metallic or paper) than a smokeless gun for the same performance, or a gun of comparable size that is blackpowder will be much less energetic to start with than a smokeless powder equivalent."

He indicates that the velocities have an impact on the terminal ballistics as well:
At low velocities like those below the speed of sound in air, a projectile that hits a target will generally poke a hole the same size as it, or possibly it may expand or flatten somewhat increasing the size of this hole. Generally speaking, though, the effectiveness at these speeds is proportional to the frontal area of the bullet – and in all cases effectiveness is by modern standards pretty underwhelming. Like poking a hole of a certain size.

Smokeless powder is more energetic, meaning cartridges loaded with it will pound-for-pound launch the same bullet at a higher velocity than a blackpowder round will. Rounds traveling above the speed of sound may exhibit more dramatic effects, disrupting organs near but not directly in the path of the bullet – at lower velocities, say 1,200-1,400 ft/s you might think of this as getting a slight free caliber boost.
He also notes that newer bullets have better designs, making them more effective at expanding, and doing so consistently.  Also, some of the battlefield deadliness of the old blackpowder projectiles was simply due to the poor medical care available at the time.

It got me thinking, though, about anecdotes that I've heard or read about some of the large, blunt bullets being able to drop game faster--i.e., a killing shot--than other loads. As I pointed out in my prior post, it is often the case that anecdotal evidence is no evidence at all--that is, even if the story isn't exaggerated or a falsehood, it may represent an outlier rather than the norm. So, is there any truth to these stories?

Somewhat surprisingly, I found some information on this very topic. The first one, which directly addresses the issue, is a paper entitled "Wound Ballistics: Minié Ball vs. Full Metal Jacketed Bullets—A Comparison of Civil War and Spanish-American War Firearms" (PDF), published in Military Medicine in 2009. That article notes that:
The late nineteenth century saw the development of a “full metal jacketed bullet” as a means to improve military firearms by increasing the range and accuracy over solid lead bullets. The changes in bullet design were also thought to have an effect on the types of wounds seen with battle casualties. When comparing casualties from the American Civil War to the Spanish-American War, observers noted less severe wounds. Borden also noted a decreased reported mortality among hospitalized patients with extremity wounds: from 13.8% to 1.6% (lower extremity) and 6.5% to 0.2% (upper extremity) when comparing casualty statistics of the Civil War to those of the Spanish-American War.
Interestingly, the Minie Ball was apparently more injurious than the just plain round lead balls. Again, from the article:
The conoid bullets [i.e., Minie Ball] varied in size and weight, but were generally between 0.54 and 0.58 inches and weighed approximately 29.1–35 grams (450–540 grains). 2,3 Use of the conoid bullets, or Minié balls, changed the tactics of mid-nineteenth century wars, including the American Civil War. Surgeons also noticed there was increased wounding sometimes seen with Minié balls.4,5 Otis described the increased destructiveness of the Minié ball when comparing wounds made with Minié balls compared with the older musket ball.
The article, however, concentrates on the different terminal ballistics of the Minie Ball versus the full metal jacketed .30 round used in the Krag-Jorgenson rifle based on tests using ballistic gelatin conducted in the 1980s at Letterman Army Institute of Research. The article sets out the finer points of the gelatin used, testing for consistency, distance from target, and so on. The test assumed a 15 cm depth as representing the maximum depth of a shot through a thigh. The results of the test were as follows:
Muzzle velocities of the rifled musket were significantly less when compared with the Krag-Jorgenson rifle, averaging 944 fps (±116; range, 809–1085) vs. 1852 fps (± 22.5; range, 1820–1878), respectively ( p < 0.001). Maximum permanent tract diameters in the first 15 cm of the musket wound track were significantly greater than the rifle, averaging 16.3 mm (±2.6, range, 14–20) vs. 9.2 mm (±3.2; range, 7.5–15), respectively ( p = 0.005). Maximum temporary cavities within the first 15 cm of gelatin were also significantly larger, averaging 121 mm (±5.4; range, 115–130) vs. 38.6mm (± 8.8; range, 30–53) ( p < 0.001). Bullet weights were also significantly larger, totaling 29.7 grams (±1.3; range 28.2–31.5) vs. 14.18 grams (±0.01; range 14.17–14.19) ( p < 0.01). Using grains, bullet weights were 458.3 grains (±20 grains; range 435.2–486.1) vs. 218.8 grains (±0.15; range 218.7–219).  
Using the entire path through the gelatin, as opposed to the first 15 cm as listed in the previous paragraph ( Fig. 5 ), the Krag-Jorgenson bullet averaged 918 mm (range 865–930 mm) total penetration, with an average maximum temporary gelatin cavity of 128 mm (range 110–157mm). This occurred at an average penetration of 485 mm (range 446–510 mm). 
 In contrast, the musket’s bullet traveled an average maximum distance of 685 mm (range 500–780 mm) through the gelatin. The maximum temporary cavity was achieved at an average of 118 mm (range 100–150 mm) depth. The maximum temporary cavity averaged 123 mm (range 115–135 mm). 
Translated into more readable terms:
 In the present study, the Minié ball caused more disruption of ordnance gelatin with both permanent and temporary cavity over the depth of penetration associated with a thigh and torso. The permanent cavity represents the area touched by the projectile as it passes through. For soft tissue with an intact vascular supply, the amount of tissue damage is proportional to the size of the projectile. The temporary cavity is a transient lateral displacement of tissue. Elastic tissue, such as skeletal muscle, may be pushed aside and bruised. Tissue in this area should heal up uneventfully. Inelastic tissue, such as bone or liver, may become fractured by this mechanism. Both the permanent and temporary cavity measurements were significantly larger through the fi rst 30 cm with the Minié balls when compared to the rifle, despite a near doubling of muzzle velocity seen with the rifle. 
The maximum temporary cavity for the Krag-Jorgenson rifle occurred at almost 50 cm, outside of the average thickness of a torso, with relatively minimal disruption of gelatin occurring in the first 30 cm. 
The authors also addressed issues concerning differences in medical treatment:
 During the Spanish-American War, William Borden, a U.S. Army surgeon, noted that the wounding effects in soft tissue of the full metal jacketed bullet were less when compared to older Minié balls.  
 This allowed for wounds through the soft tissue only to be treated nonoperativley in more cases than had occurred during the Civil War. He also noted that improved surgical techniques of asepsis or antisepsis contributed to the improved results.
This decreased mortality is usually attributed to improvements in medical care during this period, but the transition from Minié balls to full metal jacketed bullets may have also played a role.
 
Nicholas Senn, MD, a surgeon on active duty from Chicago University, also treated injured soldiers from the Spanish American War and found that the wounds to soft tissue were less severe when the newer bullets were used.
The authors concluded:
Various factors are involved with gunshot wounds. The projectile diameter, weight, shape, and composition are all factors. The two projectiles used in this study were different in all bullet variables. The bullets used with the Civil War rifled musket weighed on average twice as much, were less aerodynamically shaped, and were made entirely of soft lead. 
There are some important findings for those who study gunshot wounds today. Increased velocity is often cited as a factor, and by some authors the most important factor, causing increased wounding. The muzzle velocity of the Krag Jorgenson rifle was nearly double that of the rifled musket shots (average 1852 fps vs. 944 fps), yet is associated with less destructive wounds in both the present study and historical data. 
An article entitled "Theodor Kocher and the Scientific Foundation of Wound Ballistics" (PDF), by Martin L. Fackler, M.D., and Paul Dougherty, M.D., published in Surgery, Gynecology & Obstetrics (Feb. 1991), also notes the more extensive tissue damage from the older soft lead projectiles compared to the the full metal jacket bullets of that time period.

Another article of interest which I found was "The Effects Of The Meplat On Terminal Ballistics" by Nathan Foster--an article I had cited to in an earlier post on why wadcutters were once recommended for self-defense loads. Foster's basic conclusion is:
In plain terms, a wide flat pointed solid non expanding bullet, even if driven at handgun velocities, creates disprortionate to calibre wounding where a pointed, non expanding bullet would create a calibre sized wound. It is this dis-proportinate to calibre wounding that is of most interest to the hunter as it is this mechanism that promotes fast clean killing.

The physics involved in wide/ flat meplat wounding are very simple, the flat point meets huge resistance on impact causing the water in flesh to be forced violently away from the path of the bullet, this in turn results in broad wounding. At velocities above 1700fps and using a wide calibre, the .45-70 (.458") which this article is focused around, entry wounds using the widest possible meplat may be up to an inch in diameter with the wound channel slightly larger and remaining the same diameter for several feet. This opens up both the possibility of both broad wounding with solid projectiles combined with penetration not normally available with expanding type projectiles.

At this point it must be noted that, the higher the impact velocity, the greater the resistance. This occurs simply because the water molecules of the animal, cannot move away from the flat point bullet at relative speeds. So as velocity is increased, wound channels increase in diameter however penetration may not necessarily be deeper due to increased resistance at the target. Pointed FMJ projectiles do not seem to show much difference in wounding or penetration at varied velocities. As an example, a 147 grain 7.62 FMJ projectile fired from a .300 Win mag creates the same size permanent wound cavity as it does when fired from a .308 Win rifle. Some extra bruising does occur throughout the lungs however the actual speed of killing remains unchanged and kills with this projectile on medium game are generally slow.

Oddly, although entry wounds with wide flat meplat bullets are almost always large, non expanding bullets of this style do not seem to produce hydrostatic shock at the typically low muzzle velocities produced by big bore rifle and handgun cartridges. By hydrostatic shock, I mean the ability of the projectile to send a shock wave through the ribs and into the spine with such speed that the central nervous system shuts down the brain (temporary coma) during which time the vitals bleed out before the animal regains conciousness, giving the illusion that it has died 'instantly'.

Due to the fact that slow, non expanding wide, flat meplat projectiles do not produce any shock effect whatsoever, when using such bullets on dangerous game, hunters are advised to expect clean but delayed kills, a potentially deadly situation. Flat meplat non expanding bullets definitely give optimum results when striking major bones. When bones are hit, wound channels change from being consistant 1 to 2" wide wound channels to much more dramatic wounding. When this type of bullet strikes bone, the fragments that separate tend to be very large and incapacitating.

On average, again using the .45-70, wound channels created by flat meplat non expanding projectiles are about four times the size of the original .458" calibre hard cast bullet however expanding projectiles in .45-70 will normally produce internal wounds twelve times their original bullet diameter at close ranges and in high velocity loadings. Needless to say, expanding bullets are capable of producing faster kills. The use of a flat meplat non expanding bullet therfore requires careful consideration.

As stated, wide, flat meplat non expanding projectiles are typically slow or 'delayed' killers, even with good shot placement. This can pose serious problems when hunting large dangerous game. Worse still, in a moment of intense stress such as during a charge, poor shot placement by the hunter may lead to minimal wounding where a premium controlled expanding bullet may have been capable of more devastating wounds. It is a tough call, on frontal shots, the flat meplat non expanding projectile driven at moderate velocities, even if missing the vitals or forwards locomotive muscles and bones, still has the potential to smash pelvis and rear leg bones. Several reports indicate that hunters have indeed anchored large heavy animals in this way.

There is not only great room for experimentation with wide meplat bullets, but also expanding wide meplat bullets, an area which most manufacturers have yet to tap into. Authorities on the subject of wide meplats generally view .300" as being the minimum and .360" being the maximum practical width for meplats of .458" calibre. These measurements prove true when tested on game and the difference that an .060" (1.5mm) increase in meplat width makes to wounding and fast killing is often dramatic.
Anyway, read the whole article and examine the photographs. The author notes that a flat meplat appears to be a game-changer once you reach .38 caliber or larger.

A couple other notable articles/sites I found were "Shooting Holes in Wounding Theories: The Mechanics of Terminal Ballistics" (and, while I haven't had time to peruse them, I would note that there are many other articles on terminal ballistics at the foregoing site), and this page on terminal ballistics which has collected a large number of illustrations of the results of gelatin tests for various calibers.

So, my conclusion is that there is validity behind the anecdotes of using large blunt bullets over medium and small modern bullets. Specifically, the soft lead Minie Ball obviously showed increased tissue damage over the smaller, but higher velocity .30 caliber cartridges available at the time of the Spanish American War. Knowing what we do now about terminal ballistics, this is not surprising, but evidently was unexpected for many knowledgeable people in the late 1800s. Moreover, the use of a non-expanding meplat bullet of large caliber seems to offer certain advantages over even modern expanding bullets under certain circumstances. Being a simple man, I just enjoy the loud "smack" that I get from a blunt, large caliber bullet striking a water jug that seems to be missing from smaller bullets.

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