An Interview With Duncan MacPherson

By Joel Grant

One of the more interesting aspects of the JFK case is the almost complete dichotomy of views between mainstream physical and medical scientists and most of us amateurs. The forensic pathologists, examining the original autopsy materials, say that JFK was shot twice from behind and only from behind. NAA experts say that, to a very high degree of probability, the lead fragments removed from John Connally's wrist match the lead in CE399 and the fragments removed from JFK's brain at autopsy match one of the large fragments found in the front of the limousine (and ballistically matched to CE139, Oswald's rifle) as well as two fragments of lead found underneath Nellie Connally's seat.

Perhaps the number one reason why people doubt that JFK was shot only from the rear is the gruesome movement of the President's head and upper trunk, backwards and to the left, immediately following frame 313 of the Zapruder film, the frame in which we see JFK's head explode. Surely, it is reasoned, a movement like this could only come from the direct force of a bullet - fired from the front.

And yet, as we have seen, wound ballistics scientists point out that no small arm yet invented has the power to physically knock a person over like that. Whatever caused JFK to hurtle backwards and to the left has to be explained by some other force or forces.

Enter Duncan MacPherson.

You've heard about rocket scientists? Well, since 1989 Mr. MacPherson has been an independent technical consultant to organizations interested in space flight activities. Not that MacPherson decided, 8 years ago, to take this up as a hobby.

Back in 1959 he developed a new guidance technique and the equations that were used to guide the Mercury astronauts into orbit on the Atlas launch vehicle. These equations were modified under his supervision to control Gemini and, later, Apollo launches. Both his BS and MS degrees were won at MIT's Honors Course in Mechanical Engineering.

Since the late 1960's, following those wonderful Summers of Love, MacPherson branched into Systems Engineering, relating primarily to trajectory dynamics. (I'm taking this, by the way, from the dust cover of his excellent book, of which more, immediately, anon)

I first heard about Mr. MacPherson when I read his article: "A Simplified Penetraton Depth Correction for Data Taken in Non-Standard Gelatin" in Volume 2, No. 2, of the "International Journal of Wound Ballistics." I later discovered that Duncan MacPherson is the author of the now-famous (within the wound ballistics community and other communities interested in the interaction between bullets and bodies) book: Bullet Penetration: Modeling the Dynamics and the Incapacitation Resulting From Wound Trauma. (El Segundo, CA, 1994, Ballistic Publications) Just in case your local bookstore doesn't have this book, you can order it as follows:

Ballistic Publications, Dept NH, Box 772, El Segundo, CA 90245. $39.95 (plus tax for CA residents); [Law enforcement officers receive a reduced price of $29.95].

Although, as we will see in the interview, Mr. MacPherson modestly claims that his book is not of interest to the general public, I do think that serious students of the JFK case should get their hands on it. Please note: this book is NOT about the wound ballistics of the JFK case. It is strictly a scientific study of bullet penetration. And it is unique, to the best of my knowledge.

All other bullet penetration/wound ballistics commentaries I have read have fallen into one of two camps: theoretical or empirical. Either someone sits around crunching equations, or someone gets out guns and ammo and starts blasting away. The former approach needs to be tested against nature. The latter approach is ideal for determining what is possible, or even likely, under certain very specific conditions, but cannot, by itself, give us a general model of bullet penetration and what kind of effects that might have upon what MacPherson calls "WTI" or Wound Trauma Incapacitation.

The heart of the book is an exploration of what dynamic factors enter into the act of bullet penetration, and what that might mean in terms of the kind of trauma suffered by the human target. Many ballistics researchers in the past have mistakenly (according to MacPherson) equated damage to energy. The more energetic the bullet, the more damage. This is wrong, according to MacPherson, and he explains why in precise and exhaustive quantifiable terms, all of which are tested against actual bullet/tissue simulant studies.

Between the two of us, if the entire book were like much of it - reams and reams of equations so imposing they look like they could not only bake cakes but order the oven to turn itself up or down - I wouldn't be writing this. But MacPherson realizes that not every reader is an engineer or physicist. He would like members of the law enforcement community to be able to read and understand his model, so he does a good job of explaining things in ways that us ordinary folk can make sense of. To take just one example, here's an analogy relating to the concept of why it isn't appropriate to look at only total energy deposit and relate it to damage: (from p. 14)

1) Consider again a jacketed bullet fired into a tank of water large enough so that the bullet is slowed down and comes to rest on the bottom without having any deformation. During the process the water was agitated and had kinetic and probably potential energy (in water raised by the splash), but the water will eventually stop moving and again have no kinetic energy. All of the bullet kinetic energy has been absorbed by the water, but where is the damage? In this case the bullet causes no damage at all, no matter how high its kinetic energy may be.

Now even I can understand that. But what does this have to do with bullets and bodies, and how can I apply it to the JFK case? I say: read the book. But since (let's be honest about it) Bullet Penetration isn't exactly the lightest of the light reading, and required a bit of clarification in my mind, and since I wanted to solicit MacPherson's views of some of the wound ballistics aspects of the JFK case from yet another wound ballistics scientist (I have already interviewed Dr. John Lattimer and Dr. Martin Fackler), particularly one coming from more of an engineering than a medical background, I asked Mr. MacPherson if he would consent to a written interview, for public distribution. He kindly consented.

JOEL GRANT: Could you tell us a bit about your educational and career background, beginning with college?

DUNCAN MacPHERSON: I think the brief summary in the dust jacket of my book is a fair summary of this.

[see the introduction for this info. The short version: he's a rocket scientist. jg ]

G: How long have you been interested in wound ballistics?

MacP: I had never thought much about it until the October 1975 issue of the American Rifleman (the NRA magazine) published an article praising the Relative Incapacitation Index (RII) produced by the NIJ (an agency in the Department of Justice) as a scientifically valid answer to the "stopping power" issue. This whole RII concept was badly flawed technically, and I wrote an article in response pointing out the errors and problems. The editor of the American Rifleman declined to publish this article on the basis of "extending a controversy without settling anything" (the NRA is no more standup than any other large organization when it comes to admitting mistakes). This article was eventually published in the April 1976 Guns and Ammo. In 1992 Dr. Martin Fackler was sent a copy of this article by one of his associates. Fackler immediately contacted me to provide him with engineering input on a few wound ballistics issues, and I have been more or less involved with professional wound ballistics ever since.

G: Are you a shooter? If so, what kinds of guns do you own?

MacP: At various periods in my life I have been an active shooter of rifle, shotgun, and handgun; I am less active now due to other commitments.

G: Can you summarize the thesis of your book Bullet Penetration?

MacP: I don't think there is any thesis unless you want to consider the position that wound ballistics can be treated strictly on the basis of scientific experiment and inquiry a thesis. Bullet Penetration is really a technical book intended for readers with a serious interest in wound ballistics; it can be informative and useful to those without technical training, but is not the gee whiz nonsense that fills up most "gun magazines". Wound ballistics is understandable strictly on the basis of physics and physiology; statements about "power" in any form may make exciting reading, but are almost always devoid of useful information. Bullet Penetration summarizes most of what is known about wound ballistics that relates to incapacitation from handgun bullet trauma, and more importantly, gives a model of bullet penetration in soft tissue. This bullet penetration model is a true technical advance in that it provides new analytical capabilities and insights, and is already being used by at least some ammunition manufacturers in ammunition development.

G: Why is it important to the general public to understand bullet penetration?

MacP: It isn't.

G: Is this particularly important to law enforcement personnel?

MacP: Many law enforcement officers have been killed because they were using inadequate ammunition; they were using inadequate ammunition as a result of bad information. The bad information almost always comes from "gun magazine" writers whose credentials are related to the fact that they write a lot of articles, and not because they have any real training in or understanding of any aspect of the technical disciplines related to wound ballistics. In some instances, these writers appear to have ties to the manufacturers of the ammunition they tout. The International Wound Ballistics Association (IWBA) is a non-profit corporation devoted to scientific study of wound ballistics; the IWBA has no financial ties of any kind to ammunition or other products and does not endorse products.

The IWBA has a many members who are law enforcement officers, and aids and encourages them in understanding wound ballistics and in doing their own ammunition testing rather than relying on the opinions of others.

G: What factors are the most important in determining a bullet's ability to penetrate with deadly effect, and what is the most important factor in deadly effect?

MacP: You ask about deadly effect, rather than the more important incapacitation from wound trauma; I will deal with both, but only briefly (one chapter in Bullet Penetration is devoted entirely to this subject). Bullet placement is most important in either case, but there are complications. Only bullet impact that affects the central nervous system (CNS) can cause rapid physiological incapacitation. Incapacitation will not necessarily cause death (e.g., quadriplegics can live indefinitely). On the other hand, wounds that are unavoidably fatal will not necessarily cause rapid incapacitation. A bullet must penetrate deep enough to reach vital structures in the body to cause either death or physiological incapacitation.

G: It is common knowledge that, as captured by Abraham Zapruder, President Kennedy's head and upper torso lurch energetically immediately following the explosion of his head. Could this movement have been caused by the directly transferred momentum of a bullet? That is, can a bullet "push" somebody like that?

MacP: No, and no. The movement of a body due to bullet momentum cannot be greater than the movement of the same body if it was holding the gun that fired the bullet. This is a result of elementary physics and is not disputed by anyone who understands physics. The major frustrating feature of the Kennedy assassination phenomenon is the willingness of people to pretend to talk authoritatively on subjects they know absolutely nothing about, especially things related to firearms. This body recoil is one favorite. Another is the "puff of smoke from the grassy knoll"; the theory here seems to be that someone shot Kennedy with a flintlock (modern firearms don't make a puff of smoke on firing as black powder rounds do).

G: If the effects observed on the Zapruder film are not the result of a direct "push" by a bullet, what could account for JFK's movements?

MacP: In general, body movement in response to nervous system trauma is a result of contractions in body muscles. This is related to movements of your leg when a doctor raps you on the knee with his little mallet; your leg moves because a nerve induces a muscle contraction, not because it was driven into motion by the force of the tiny rap with the mallet. The slightly peculiar location of Kennedy's arms after the 399 bullet impact is known as Thorburn's position, after a description by Dr. William Thorburn in an 1889 paper on injuries to the area of the spinal chord damaged by bullet 399. In addition to this effect, simulations have shown that bullet strikes to the skull that result in blowing out a significant hole upon exit result in skull recoil towards the bullet entry direction. The dynamics of this are a little complicated, but are more related to the pressure inside the skull cavity created by the bullet passage than to effects directly related to the bullet movement. The dynamics of this kind of impact were demonstrated independently in testing by Dr. Luis Alvarez and by Dr. John K. Lattimer et al.

G: Have you had a chance to review the JFK-related wound ballistics work of Drs. John Lattimer and Martin Fackler? If so, can you provide a brief critique?

MacP: I have read this work and have referred to it to look up Thorburn's name in the previous answer. The main aspect of the Kennedy assassination that would surprise most people is how uncontroversial the wound ballistics aspects are among the physicians in the country who are most experienced in gunshot trauma (I am not one of these, but have talked to several). It is a sad truth that most autopsy reports are full of errors and inconsistencies which are obvious to any careful review; it shouldn't be like this, but it is. The problems with the Kennedy autopsy do not require a conspiracy to explain, they are more or less business as usual exposed to the glare of careful examination. Likewise, the work of Lattimer and Fackler is simply a very sound, complete, and careful examination and reconstruction of that facts that should be the standard in all cases, but isn't.

Some argument can be made in the typical investigation that the talent and resources just are not available to meet a first class standard, but one can hardly argue that this situation is applicable to the Warren report. The Warren commission should have used all of the best talent available to make the most complete analysis possible, but they didn't. In fairness, it is always easier to criticize than to perform.

G: Is it possible to deform a bullet the way CE399 is deformed by firing the bullet into water?

MacP: Probably not. Bullet 399 really isn't deformed much; a point often made by those who dispute the "single bullet" conclusion. The bullets used in this assassination are much more resistant to deformation than most rifle bullets. The major effect in bullet 399 is "toothpasting", i.e., a small amount of the lead core has been squeezed out of the jacket base like toothpaste from a tube. This probably occurred when the bullet hit Connally's ribs at a high yaw angle after it had been considerably slowed by travel through soft tissue (a bullet in a reconstructed firing showed deformation similar to and slightly larger than bullet 399). The bullet would yaw in water, but probably would not "toothpaste" without contact with a hard object.

G: Is the deformation of CE399 inconsistent with its having caused all of JFK's and JBC's non-fatal wounds?

MacP: No. Reconstructions prove that bullet 399 is consistent with having caused all these wounds.

G: Are you aware of the claim that CE399 was "switched" from a six-groove bullet to a four-groove bullet? If so, will you give us your professional opinion?

MacP: No knowledge about this claim. For about 30 years, I have paid almost no attention to any aspect of the Kennedy assassination not directly related to wound ballistics.

And there you have it. One more scientist who has done original wound ballistics work who agrees with all the other wound ballistics scientists with any knowledge of the JFK case: the popular opinions regarding the movements of JFK's head and upper torso following z-313 and the condition of CE399 are not at all inconsistent with the conclusion that all of Kennedy's and Connally's wounds were caused by shots fired from behind the limousine.

It is stuff like this that convinces me that, long after the emotional partisanship fades away, history's verdict will be that Lee Harvey Oswald is the villain of this piece.

Joel Grant

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