**Mismatched bullet identification procedures-unusual
for over size smooth bore firearms.

J. K. Sinha.

Identification of projectiles fired from smoothbore, improvised
and home made firearms-- Author's Ph.D.thesis

**Part of a chapter of thesis--    Brief description**

      Unusual identification procedure is adopted for mismatched bullets fired from oversized firearms-specially smooth bore. It differs with the type of over size bore and chamber alignment. The variation in bore size from breech to muzzle and extent of chamber alignment significantly influence barrel marks on fired bullets. Since bullet makes random contacts in over sized bore, distinct dissimilar striations from the same barrel is possible. A careful evaluation is necessary while forming opinion on dissimilar marks, whether bullet is positively linked or not. In general, no opinion should be formed on dissimilar marks.
       Three to five test bullets of same caliber as that of evidence bullets are fired from over sized firearm. Test bullets are compared amongst themselves under a comparison microscope. Similar/dissimilar patch/patches of striations on test bullets determine proper identification procedure.
  1. If patch/patches of straight/inclined striations are repetitive and similar on all test bullets, then it is obvious that the questioned over sized firearm has a misaligned chamber. The repetitive patch is compared with the patch/patches on evidence bullets. If there is a positive match then linkage is established. At least one patch of striations must be repetitive and similar on test and evidence bullets. Besides repetitive patch/patches, there may be dissimilar marks due to random contacts at different places.

    patch striation matching
    Striations matching
    Repetitive patch on test and similar patch on evidence

  2. The procedure of obtaining proper tests is modified if there is no repetitive patch. Instead of test firing, slightly over sized lead bullets/slugs are pushed through the barrel almost straight from chamber to muzzle end. A positive match of one or more patches of straight striations on pushed through test and evidence bullets indicates linkage even if distinct dissimilar patch is present. A caution is needed if there is no positive match. No Opinion on dissimilar marks should be formed .

    pushed through test<br> and evidence bullet matching

    Striations matching
    Evidence bullet and oversized pushed through bullet

  3. If striations on test bullets are either absent or insignificant, then it becomes evident that the firearm is over sized and the chamber is not excessively misaligned. In the absence of identifiable striations, bullet-firearm linkage cannot be established. Only physical and chemical examination can be carried out to ascertain whether the evidence bullet appearing like unfired is a fired one. The portion of the bullet carrying faint scratches, if any, may also be examined for presence of transferred metal of barrel fouling by SEM-EDXA.
    presence of iron-EDX elemental analysis
    Presence of iron on faint scratch on jacketed portion of a .315
    soft nose bullet fired from over sized home built firearm.




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    ** Theory, experimental details and illustrative photographs in author's forthcoming book titled
           " Unusual forensic ballistics and shooting reconstruction"

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