APPENDIX X - Expert Testimony

FIREARMS AND FIREARMS IDENTIFICATION

Three experts gave testimony concerning firearms and firearms identification: Robert A. Frazier and Cortlandt Cunningham of the FBI, and Joseph D. Nicol, superintendent of the Bureau of Criminal Identification and Investigation of the State of Illinois. Frazier has been in the field of firearms identification for 23 years, following a l-year course of specialized training in the FBI Laboratory. Cunningham has been in the field for 5 years, having also completed the FBI course. Nicol has been in the firearms identification field since 1941, having begun his training in the Chicago police crime laboratory. Each has made many thousands of firearms identification examinations.1 Frazier testified on the rifle, the rifle cartridge cases, and the rifle bullets; Cunningham on the revolver, the revolver cartridge cases, the revolver bullets, and the paraffin test; and Nicol on all the bullets and cartridge cases and the paraffin test. 2 Nicol's conclusions were identical to those of Frazier and Cunningham, except as noted.

General Principles

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 tire 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