Inconsistent Metallurgical Claims

    My old bandleader at MIT, John Corley, always used to exhort us to get the beginning and endings of pieces right because he said, "The audience will remember the first note and the last note, not the stuff in between." So it can be with scientific articles as well—most readers remember the first parts and the last parts more than the boring details in the middle.
    Normally, that doesn't present a problem, because the beginnings, middles, and ends will be consistent with each other. But not herethe beginning and the ending of this article present considerably stronger statements about metallurgy than the middle does. Its followers, most of whom are not in a position to independently evaluate the details, are choosing to remember the beginning and the ending, and are not realizing how critically they differ from the truths in the middle.
    It starts with the very first word of the title"Proper." This word strongly implies that the article is contrasting itself with earlier work that is "improper." To illustrate the pattern of stronger and weaker claims in the rest of the article, I have segregated them by the order of their sections in the article. Although it is a truism, it should not be forgotten that stronger and weaker claims for the same thing cannot both be true. All numbered sentences below are verbatim from the article.

Abstract
      (1) Microsegregation of trace and minor elements during lead casting and processing can account for the experimental variabilities measured in various evidentiary and comparison samples by laboratory analysts. (Strong)
    (2) Thus, elevated concentrations of antimony and copper at crystallographic grain boundaries, the widely varying sizes of grains in MC bullet lead, and the 5-60 mg bullet samples analyzed for assassination intelligence effectively resulted in operational sampling error for the analyses. (Strong)
    (3) This deficiency was not considered in the original data interpretation and resulted in an invalid conclusion in favor of the single-bullet theory of the assassination. (Absolute statement)

Introduction
    (1) However, VPG did not interpret his measurements with knowledge of basic metallurgy of lead alloys, standard lead smelting, and bullet manufacturing processes. His conclusions are unsupported from those vantage points. (Strong)
    (2) Finally, he was unaware that the small sample size he was constrained to contributed to variability in his measurements because some of the elements he quantified were not distributed uniformly within the samples as this scale.  (Strong)

Trace Analysis
    (1) An investigator cannot interpret the compositional analyses without regard to the realities of bullet production. (Strong)
    (2) He or she must therefore have knowledge of, or at least consider the metallurgy of, lead alloys, lead smelting practices, as well as ammunition distribution practices. (Strong)

Essential Metallurgy
    (1) The common occurrence of segregation (both microsegregation and macrosegregation), as discussed below, explains VPG's observations and the variability in his measured antimony and copper data. (Absolute statement)

MC Grain Size
    (1) Using Figs. 3 and 4 as visual aids, if the sample size of a lead specimen approaches the grain size, and the antimony and copper trace elements are segregated at the boundaries, then the variability of sample compositions will increase. (Strong general prediction)
    (2) For example, if all samples were large enough to contain on the order of 50 or more grains, they will encompass a good average quantity of both grain-boundary material and interior grain material and will be reasonably representative of the true average composition of the alloy. (Strong specific prediction. Note that the FBI used triplicate 60-g samples to construct its huge database on bullets, and their variabilities were typically only 3%5%.)
    (3) However, if the samples are only the size of, e.g., one to three grains, then each sample will likely contain different relative proportions of grain-boundary and interior grain material. This situation can result in increased compositional variability among ostensibly equivalent samples. (Weaker prediction)
    (4) The answer to questions of whether sample sizes were appropriate in the JFK assassination investigation, and whether they could have contributed to variability of the results, is then effectively reduced to that of assessing grain sizes. (Weak/strong statement)
    (5) Hence, some or all of the variability seen in VPG's antimony and copper measurements could be attributed to small sample sizes. (Weaker statement)
    (6) Certainly, 510 mg samples should be suspect with respect to being representative of the bulk composition. (Very weak statement that also appeals to a mythical "bulk composition" that is not supported by the actual data)
    (7) The end-result of these metallurgical considerations is that, from the antimony concentrations measured by VPG in the specimens from the JFK assassination, there is no justification for concluding that two, and *only* two, bullets were represented by the evidence. (Very strong statement that derives from the weaker statements above)

Conclusions
    (1) The large and variable grain sizes found in bullets from WCC MC ammunition lots 6000 and 6003 show that the 150 mg specimen sizes that VPG was restricted to for the JFK analyses could have contributed to, or been the sole source of, the variability found in the antimony and copper data. (Weak again)
    (2) Hence, the relatively small differences reported in antimony composition alone in the JFK data are not adequate to differentiate among the possibilities of a single or multiple bullets. (Strong)
    (3) ... a conclusion of material evidence for only two bullets in the questioned JFK assassination specimens has no forensic basis. (Absolute statement)

Overall pattern
    These statements begin strong, waffle in the middle, and end strong. Support from the middle is weak to the point of being absent. (This will be seen more on the page on The metallurgical logic.)

Which of the conflicting claims to hold the article to?
    It seems to me that any argument that makes stronger and weaker claims on the same subject should be held to the strongest of the claims. The relevant claim in this case is the absolute claim under Essential Metallurgy: "The common occurrence of segregation explains VPG's observations and the variability in his measured antimony and copper data." This amounts to saying that Guinn was just measuring crystalline effects in the MC lead, and that this lead was no different from any other. There were no two groups, only random variations in antimony from crystalline effects.

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