Report of the President's Commission on the Assassination of President John F. Kennedy

第二章 With the assistance of Agent in Charge Sorrels of the

Chapter II, with the assistance of Agent in Charge Sorrels of the FBI, examines the forensic firearms evidence related to the assassination. The chapter covers expert firearms identification methodology applied to cartridge cases, a physical description of the 6.5-millimeter Mannlicher-Carcano rifle (C2766) recovered from the Texas School Book Depository, the 6.5-millimeter Western Cartridge Co. ammunition used, the three expended cartridge cases and bullets recovered from the building, the President’s car, and Governor Connally’s stretcher, and the .38 Special Smith & Wesson Victory Model revolver taken from Oswald at his arrest.

Expert Firearms Identification of Cartridge Cases

Firearms identification of cartridge cases relies on microscopic examination of individual characteristics—dents, ridges, bumps, and depressions—left on the breech face and primer by the weapon. A photograph can show the location and type of marks but cannot convey their height, width, or relationship; actual identification requires a mental, visual comparison between the questioned and test specimens under a microscope. According to firearms expert Frazier, a layman could not perform this analysis because he would not know what to look for, the marks must be mentally sorted and compared across many areas, and irrelevant features (such as pre-existing depressions in the primer) could lead to erroneous conclusions. Identification is therefore a matter of expert interpretation rather than a simple point-for-point comparison. Even when individual marks differ between two cartridge cases fired from the same weapon—due to differences in metal flow, pressure, firing-pin wear, or primer hardness—identification is based on the overall pattern, contour, and nature of the similarities rather than the absence of dissimilarities. A bullet or cartridge case cannot always be identified with the firing weapon if it is too mutilated, if the weapon’s microscopic characteristics have changed between firings due to wear, corrosion, or cleaning, or if the weapon marks bullets inconsistently.