A cartridge, or round of ammunition, is composed of a primer, a cartridge case, powder, and a bullet. The primer, a metal cup containing a detonable mixture, fits into the base of the cartridge case, which is loaded with the powder. The bullet, which usually consists of lead or of a lead core encased in a higher strength metal jacket, fits into the neck of the cartridge case. To fire the bullet, the cartridge is placed in the chamber of a firearm, immediately behind the firearm’s barrel. The base of the cartridge rests against a solid support called the breech face or, in the case of a bolt-operated weapon, the bolt face. When the trigger is pulled, a firing pin strikes a swift, hard blow into the primer, detonating the priming mixture. The flames from the resulting explosion ignite the powder, causing a rapid combustion whose force propels the bullet forward through the barrel.
The barrels of modern firearms are “rifled,” that is, several spiral grooves are cut into the barrel from end to end. The purpose of the rifling is to set the bullet spinning around its axis, giving it a stability in flight that it would otherwise lack. The weapons of a given make and model are alike in their rifling characteristics; that is, number of grooves, number of lands (the raised portion of the barrel between the grooves) and twist of the rifling. When a bullet is fired through a barrel, it is engraved with these rifling characteristics. For example, all S. & W. .38/200 British Service Revolvers have five grooves and five lands, which twist to the right, and bullets fired through such a revolver will have five groove and land impressions, right twist.
In addition to rifling characteristics, every weapon bears distinctive microscopic characteristics on its components, including its barrel, firing pin, and breech face. While a weapon’s rifling characteristics are common to all other weapons of its make and model (and sometimes even to weapons of a different make or model), a weapon’s microscopic characteristics are distinctive, and differ from those of every other weapon, regardless of make and model. Such markings are initially caused during manufacture, since the action of manufacturing tools differs microscopically from weapon to weapon, and since the tools change microscopically while being operated. As a weapon is used, further distinctive microscopic markings are introduced by the effects of wear, fouling, and cleaning. As Frazier testified:
Q. Can you explain how you are able to come to a conclusion that a cartridge case was fired in a particular weapon to the exclusion of all other weapons?
Mr. Frazier. Yes, sir; during the manufacture of a weapon, there are certain things done to the mechanism of it, which are by machine or by filing, by grinding, which form the parts of the weapon into their final shape. These machining and grinding and filing operations will mark the metal with very fine scratches or turning marks and grinding marks in such a way that there will be developed on the surface of the metal a characteristic pattern. This pattern, because it is made by these accidental machine-type operations, will be characteristic of that particular weapon, and will not be reproduced on separate weapons. It may be a combination of marks that—the face of the bolt may be milled, then it may be in part filed to smooth off the corners, and then, as a final operation, it may be polished, or otherwise adjusted during the hand fitting operation, so that it does have its particular pattern of microscopic marks.
The bolt face of the 139 rifle I have photographed and enlarged in this photograph [Commission Exhibit No. 558] to show the types of marks I was referring to.
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The marks produced during manufacture are the marks seen on the bolt face; filing marks, machining marks of the various types, even forging marks or casting marks if the bolt happens to be forged or cast. And then variations which occur in these marks during the life of the weapon are very important in identification, because many of the machining marks can be flattened out, can be changed, by merely a grain of sand between the face of the cartridge case and the bolt at the time a shot is fired, which will itself scratch and dent the bolt face. So the bolt face will pick up a characteristic pattern of marks which are peculiar to it.
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* * * [T]he marks which are placed on any bolt face are accidental in nature. That is, they are not placed there intentionally in the first place. They are residual to some machining operation, such as a milling machine, in which each cutter of the milling tool cuts away a portion of the metal; then the next tooth comes along and cuts away a little more, and so on, until the final surface bears the combination of the various teeth of the milling cutter. In following that operation, then, the surface is additionally scratched—until you have numerous—we call them microscopic characteristics, a characteristic being a mark which is peculiar to a certain place on the bolt face, and of a certain shape, it is of a certain size, it has a certain contour, it may be just a little dimple in the metal, or a spot of rust at one time on the face of the bolt, or have occurred from some accidental means such as dropping the bolt, or repeated use having flattened or smoothed off the surface of the metal.
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* * * [A]s the blade of a milling machine travels around a surface, it takes off actually a dust—it is not actually a piece of metal—it scrapes a little steel off in the form of a dust—or a very fine powder or chip—that tooth leaves a certain pattern of marks—that edge. That milling cutter may have a dozen of these edges on its surface, and each one takes a little more. Gradually you wear the metal down, you tear it out actually until you are at the proper depth. Those little pieces of metal, as they are traveling around, can also scratch the face of the bolt—unless they are washed away. So that you may have accidental marks from that source, just in the machining operation.
Now, there are two types of marks produced in a cutting operation. One, from the nicks along the cutting edge of the tool, which are produced by a circular operating tool—which produce very fine scratches in a circular pattern. Each time the tool goes around, it erases those marks that were there before. And when the tool is finally lifted out, you have a series of marks which go around the surface which has been machined, and you will find that that pattern of marks, as this tool goes around, will change. In one area, it will be one set of marks—and as you visually examine the surface of the metal, these very fine marks will extend for a short distance, then disappear, and a new mark of a new type will begin and extend for a short distance. The entire surface, then, will have a—be composed of a series of circles, but the individual marks seen in the microscope will not be circular, will not form complete circles around the face of the bolt.
Q. Have you had occasion to examine two consecutive bolt faces from a factory?
A. Oh, yes.
Q. And what did you find on that examination?
A. There would be no similarity in the individual microscopic characteristics between the two bolt faces.
Q. There actually was none?
A. No, there was none.[A10-3]
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Q. How are you able to conclude that a given bullet was fired in a given weapon to the exclusion of all other weapons, Mr. Frazier?
A. That is based again upon the microscopic marks left on the fired bullets and those marks in turn are based upon the barrel from which the bullets are fired.
The marks in the barrel originate during manufacture. They originate through use of the gun, through accidental marks resulting from cleaning, excessive cleaning, of the weapon, or faulty cleaning.
They result from corrosion in the barrel due to the hot gases and possibly corrosive primer mixtures in the cartridges used, and primarily again they result from wear, that is, an eroding of the barrel through friction due to the firing of cartridges, bullets through it.
In this particular barrel the manufacturer’s marks are caused by the drill which drills out the barrel, leaving certain marks from the drilling tool. Then portions of these marks are erased by a rifling tool which cuts the four spiral grooves in the barrel and, in turn, leaves marks themselves, and in connection with those marks of course, the drilling marks, being circular in shape, there is a tearing away of the surface of the metal, so that a microscopically rough surface is left.
Then removing part of those marks with a separate tool causes that barrel to assume an individual characteristic, a character all of its own.
In other words, at that time you could identify a bullet fired from that barrel as having been fired from the barrel to the exclusion of all other barrels, because there is no system whatever to the drilling of the barrel. The only system is in the rifling or in the cutting of the grooves, and in this case of rifle barrels, even the cutters wear down as the barrels are made, eventually of course having to be discarded or resharpened.
Q. Have you examined consecutively manufactured barrels to determine whether their microscopic characteristics are identical?
A. Yes, sir; I have three different sets of, you might say, paired barrels, which have been manufactured on the same machine, one after the other, under controlled conditions to make them as nearly alike as possible, and in each case fired bullets from those barrels could not be identified with each other; in fact, they looked nothing at all alike as far as individual microscopic characteristics are concerned. Their rifling impressions of course would be identical, but the individual marks there would be entirely different.[A10-4]
When a cartridge is fired, the microscopic characteristics of the weapon’s barrel are engraved into the bullet (along with its rifling characteristics), and the microscopic characteristics of the firing pin and breech face are engraved into the base of the cartridge case. By virtue of these microscopic markings, an expert can frequently match a bullet or cartridge case to the weapon in which it was fired. To make such an identification, the expert compares the suspect bullet or cartridge case under a comparison microscope, side by side with a test bullet or cartridge case which has been fired in the weapon, to determine whether the pattern of the markings in the test and suspect items are sufficiently similar to show that they were fired in the same weapon. This is exemplified by Frazier’s examination of Commission Exhibit No. 543, one of the cartridge cases found in the Texas School Book Depository Building after the assassination:
Q. Mr. Frazier, we were just beginning to discuss, before the recess, Commission Exhibit 559, which is a picture, as you described it, of Exhibit No. 543 and a test cartridge under a microscope * * *?
Mr. Frazier. Yes, sir.
Q. Could you discuss, by using that picture, some of the markings which you have seen under the microscope and on the basis of which you made your identification?
A. Yes, sir. In the photograph I have drawn some small circles and numbered them, those circles, correspondingly on each side of the photograph. The purpose of the circles is not to point out all the similarities, but to call attention to some of them and to help orient in locating a mark on one with a mark on the opposite side of the photograph. In general the area shown is immediately outside of the firing pin in the bolt of the 139 rifle, on the left side of the photograph, and Commission Exhibit 543 on the right side.
The circles have been drawn around the dents or irregularly shaped ridges, small bumps, and depressions on the surface of the metal in six places on each side of the photograph. It is an examination of these marks, and all of the marks on the face of the breech, microscopically which permits a conclusion to be reached. The photograph itself actually is a substitute to show only the type of marks found rather than their nature, that is, their height, their width, or their relationship to each other, which is actually a mental, visual, comparison on the two specimens themselves.
Q. Referring for a second to this mental, visual, comparison, Mr. Frazier, would a person without firearms training—firearms-identification training—be able to look under a microscope and make a determination for himself concerning whether a given cartridge case had been fired in a given weapon?
A. In that connection that person could look through the microscope. He may or may not see these individual characteristics which are present, because he does not know what to look for in the first place, and, secondly, they are of such a nature that you have to mentally sort them out in your mind going back and forth between one area and the other until you form a mental picture of them in a comparison such as this.
If it was a different type of comparison, of parallel marks or something of that nature, then he could see the marks, but in either instance, without having compared hundreds and hundreds of specimens, he would not be able to make any statement as to whether or not they were fired from the same rifle.
Q. Would you say that this is, then, a matter of expert interpretation rather than a point-for-point comparison which a layman could make?
A. I would say so; yes. I don’t think a layman would recognize some of the things on these cartridge cases and some shown in the photographs as actually being significant or not significant, because there will be things present which have nothing whatsoever to do with the firing of the cartridge case in the gun.
There may be a depression in the primer to begin with, and there are no marks registered at that point as a result of the firing. Unless these things are known to occur, someone may actually arrive at a different conclusion, because of the absence of similar marks.
Q. Now having reference to the specific exhibit before you, which is 559—
A. Yes.
Q. Are all the marks shown in both photographs identical?
A. No.
Q. And could you go into detail on a mark which is not identical to explain why you would get such a result?
A. Well, for instance, between what I have drawn here as circle 4 and circle 5, there is a slanting line from the upper left to the lower right on C-6. This line shows as a white line in the photograph.
On the other side there is a rough, very rough ridge which runs through there, having an entirely different appearance from the relatively sharp line on C-6. The significant part of that mark is the groove in between, rather than the sharp edge of the mark, because the sharp corner could be affected by the hardness of the metal or the irregular surface of the primer and the amount of pressure exerted against it, pressing it back against the face of the bolt, at the time the cartridges were fired. So that you would never expect all the marks on one cartridge case to be identical with all the marks on the other cartridge case.
In fact, you would expect many differences. But the comparison is made on the overall pattern, contour, and nature of the marks that are present.
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Q. Again there are dissimilar marks on these two pictures [of the firing-pin depressions on the cartridge case Commission Exhibit No. 543, and a test cartridge case], Mr. Frazier?
A. Yes; there are, for the same reason, that metal does not flow the same in every instance, and it will not be impressed to the same depth and to the same amount, depending on the type of metal, the blow that is struck, and the pressures involved.
Q. Is your identification made therefore on the basis of the presence of similarities, as opposed to the absence of dissimilarities?
A. No, that is not exactly right. The identification is made on the presence of sufficient individual microscopic characteristics so that a very definite pattern is formed and visualized on the two surfaces.
Dissimilarities may or may not be present, depending on whether there have been changes to the firing pin through use or wear, whether the metal flows are the same, and whether the pressures are the same or not.
So I don’t think we can say that it is an absence of dissimilarities, but rather the presence of similarities.[A10-5]
A bullet or cartridge case cannot always be identified with the weapon in which it was fired. In some cases, the bullet or cartridge case is too mutilated. In other cases, the weapon’s microscopic characteristics have changed between the time the suspect item was fired and the time the test item was fired—microscopic characteristics change drastically in a short period of time, due to wear, or over a longer period of time, due to wear, corrosion, and cleaning. Still again, the weapon may mark bullets inconsistently—for example, because the bullets are smaller than the barrel, and travel through it erratically.[A10-6]
The Rifle
The rifle found on the sixth floor of the Texas School Book Depository shortly after the assassination was a bolt-action, clip-fed, military rifle, 40.2 inches long and 8 pounds in weight.[A10-7] Inscribed on the rifle were various markings, including the words “CAL. 6.5,” “MADE ITALY,” “TERNI,” and “ROCCA”; the numerals “1940” and “40”; the serial number C2766; the letters “R-E,” “PG,” and “TNI”; the figure of a crown; and several other barely decipherable letters and numbers.[A10-8] The rifle bore a very inexpensive Japanese four-power sight, stamped “4 x 18 COATED,” “ORDNANCE OPTICS INC.,” “HOLLYWOOD CALIFORNIA,” and “MADE IN JAPAN”[A10-9] and a sling consisting of two leather straps, one of which had a broad patch, which apparently had been inserted on the rifle and cut to length.[A10-10] The sling was not a standard rifle sling, but appeared to be a musical instrument strap or a sling from a carrying case or camera bag.[A10-11] A basic purpose of a rifle sling is to enable the rifleman to steady his grip, by wrapping the arm into the sling in a prescribed manner. The sling on the rifle was too short to use in the normal way, but might have served to provide some additional steadiness.[A10-12]
The rifle was identified as a 6.5-millimeter Mannlicher-Carcano Italian military rifle, Model 91/38.[A10-13] This identification was initially made by comparing the rifle with standard reference works and by the markings inscribed on the rifle.[A10-14] The caliber was independently determined by chambering a Mannlicher-Carcano 6.5 millimeter cartridge in the rifle for fit, and by making a sulfur cast of the inside of the rifle’s barrel which was measured with a micrometer.[A10-15] (The caliber of a weapon is the diameter of the interior of the barrel, measured between opposite lands. The caliber of American weapons is expressed in inches; thus a .30-caliber weapon has a barrel which is thirty one-hundredths or three-tenths of an inch in diameter. The caliber of continental European weapons is measured in millimeters. A 6.5-millimeter caliber weapon corresponds to an American .257-caliber weapon, that is, its barrel diameter is about one-fourth inch.)[A10-16] The identification was later confirmed by a communication from SIFAR, the Italian Armed Forces Intelligence Service. This communication also explained the markings on the rifle, as follows: “CAL. 6.5” refers to the rifle’s caliber; “MADE ITALY” refers to its origin, and was inscribed at the request of the American importer prior to shipment; “TERNI” means that the rifle was manufactured and tested by the Terni Army Plant of Terni, Italy; the number “C2766” is the serial number of the rifle, and the rifle in question is the only one of its type bearing that serial number; the numerals “1940” and “40” refer to the year of manufacture; and the other figures, numbers, and letters are principally inspector’s, designer’s, or manufacturer’s marks.[A10-17]