The most well-known rifle shots in history are those fired November 22, 1963 from a Mannlicher-Carcano rifle in Dallas' Dealey Plaza. These were presumably fired by Lee Harvey Oswald. The bullets that killed President John F. Kennedy have ever since been the subject of controversy between the government investigators and a plethora of conspiracy theorists. The official version of the assassination is that a single crazed gunman fired the fatal shots from a sixth floor window in the Texas School Book Depository building. Various attempts to demonstrate multiple shooters on the infamous "grassy knoll" and other locations have tried to show that the assassination of the President was a conspiracy of two or more shooters.
Audio analyses performed on recordings from that event appear to show that four or more shots were fired, implying the presence of more than one gunman. However, the acoustical layout of Dealey Plaza is such that the scientific validity of those studies was called into question. Various films, pictures and eyewitness testimony implicate an additional shooter at the grassy knoll area. Then there is the infamous "magic bullet" which presumably passed thru Kennedy, then struck Texas Governor John Connally in the back, breaking four inches of one of his ribs, passing out and into his arm, and eventually lodging in his right wrist; one of the hardest bones in the body. Then this bullet, in almost pristine condition, fell out onto the stretcher as he was brought into Parkland Hospital. In all that travel, the bullet that had lost no more than 1.5 percent (2.5 grains) of its mass.
Bullet Lead Analysis of Bullet Fragments
In all, five bullet fragments were recovered from Jack Kennedy's body at autopsy and from the Presidential limousine. The original chemical analysis on these lead fragments was performed by the FBI Laboratory and by a University of California, Irvine, chemist, the late Vincent Guinn. Using the presumed best methods of the day, Guinn conducted trace metal analysis on the fragments and concluded that Kennedy was killed by two bullets, both fired from Oswald's rife.
Forensic chemical analysis in the 1960s was not as sensitive and sophisticated as it is today. Chemical and metallurgical analysis methods and instrumentation have made major advances in accuracy and sensitivity in the past forty years. The analyses performed by forensic metallurgy labs today can detect much lower levels of trace metal elements with much higher levels of accuracy and confidence.
In 1976, the FBI reported that from their analysis of the composition of the fragments, it was not possible to tell definitively if the fragments came from the same bullet. However, Guinn's conclusion was very different. He concluded that the levels of the trace element antimony came from two bullets fired from a Mannlicher-Carcano rifle. Therefore, there was only one shooter, Oswald. These results were the basis for the Warren Commission's conclusion that there was only a lone gunman.
Bullet Lead Composition
When lead is smelted and refined, the process is designed to remove contaminant elements like silver, antimony, and copper and reduce their level to that acceptable for a specific alloy or composition. Studies have shown that the level of micro-contaminant metals in bullets is not unique. Bullets poured from different batches of lead smelted months or years apart could have an identical chemical signature. In addition, bullets poured from the start of a batch could differ measurably from those poured at the end of the batch. Therefore, trace metal analysis of bullet lead does not provide a reliable chemical fingerprint like trace chemical analysis does in other areas.