The brass cartridge case was a commercial variety produced by the Remington company of the United States for use with 9mm semi-automatic pistols. These pistols come in two sizes, the standard and the smaller 'short' weapon, and this ammunition was for the latter. This 9mm short is a handy-sized pistol that could very easily be carried in the pocket of a Barbour-style coat. A number of firearms companies around the world, including Walther of Germany and Beretta of Italy, make them, but it could not be determined which make had been used to kill Jill Dando. The evidence would normally be there: the different makes of gun tend to leave characteristic marks on the cartridge, both from the firing pin which detonates the charge and from the mechanism which ejects the cartridge afterwards. In this case, however, though the marks were there they did not give a clear steer - the first indication that the gun was an unusual one.
On the outside of the case, close to the rim, police ballistics experts found six tiny indentations of a kind that was new to them. Never had a cartridge carrying such marks been used in any crime committed in Britain and nor, so far as they could establish, had anything of the kind ever been sold commercially or on the known illegal market in this country. It was unique. To understand what these marks were you need to know that in the shooting world a cartridge case is frequently used more than once. A standard round contains four components - the case, the primer, the propellant and the bullet itself - and of these the case, if only because it is made of brass, is the most expensive. So much so that it is worthwhile for regular gun users to buy the other components separately and assemble their own rounds, re-using their spent cartridges. There is, however, a slight difficulty. Hardly surprisingly, a cartridge case is distorted in shape when a gun is fired, so it will no longer be a perfect fit for a new, mass-produced bullet. The process of tightening the case around the bullet is known as 'crimping', and the marks on the case for the Dando bullet showed that it had been crimped in a most unusual way. In Britain the commonest form of crimping, traditionally, has been by means of a crimp die, essentially a piece of steel with a tapering hole in it of the required dimensions. The assembled round is simply placed in the hole and tapped or pressed until the tapering tightens the cartridge around the bullet to give the appropriate grip. Nothing could be simpler. The usual alternative to the die is the punch crimp, a jig in which the cartridge is held at points around its mouth and squeezed on to the bullet by tightening the grip. Both processes leave marks and the marks on the Dando cartridge resembled those from a punch crimp rather than a die. But there was a problem. Conventional punch crimps leave three marks and not six, and those three marks tend to be pretty well identical. The six marks on the Dando cartridge, however, were different from each other; each was slightly ragged. In fact the marks did not appear to have been made mechanically at all. In the police phrase, the cartridge case seemed to have been 'hand-tapped around' - someone tightened it around the bullet simply by placing the point of a nail or something similar against the side and tapping it with a hammer. By implication, then, this round was assembled by someone who did not have access to the machines employed by people who are putting together ammunition in any quantity. 'Hand-tapping' would be fiddly, slow and inefficient; nobody who was making even a batch of a dozen rounds would want to do it that way.
And this was only the beginning of the crimping mystery, for the ballistics experts at the forensic science service could find nothing to suggest that this cartridge case had been used more than once or that it had ever previously been separated from its bullet. The rim of the case showed a single faint mark of the kind left by the ejection mechanism of an automatic pistol; in other words, it seemed that this case had only ever been ejected from a gun once, after Jill Dando was shot. The bullet, for its part, showed none of the characteristic scratch marks left when bullets are extracted from cases manually or by machine. So why the crimping? Why had someone gone to the trouble of making those makeshift indentations when the round appeared to have been in one piece all along? It seemed almost perverse.
