Question on balistics?

Question

I know that bullets can be linked to the weapon they are fired from by the bore markings on the bullet and inside the weapon.

If all you have is a shell casing, can that shell casing be linked to the weapon that fired it? Do firing pins leave "distinguishing" marks that are unique to each fireing pin and only that firing pin?

Answer 1

They can, but it is much more difficult. If there are markings on the extraction in a semi-automatic pistol or rifle, or an automatic rifle or pistol, an argument can be made that it came from that weapon. Many times, small dents will be made on a shell casing when the case is extracted after firing. If the weapon is a revolver, then the dent in the primer may do more to exclude a weapon than make a case that the weapon in question is what was used. A bolt action, again, if the casing is somehow marked by the bolt extracting the casing from the chamber, a case can be made.

The rifling of the barrel is much more an indicator, however, a great deal of forensic information might be able to be gained by examining the spent shell casing.

In all cases, when a shell is fired, either from a revolver cylinder or in a firing camber of a bolt action or semi-automatic or automatic weapon, when the brass expands, it will make marks on the casing than can be traced to a weapon. More marks, so yes, information can be traced to the chamber or cylinder.

Answer 2

Yes they do. Both of these can be used in court but this evidence alone cannot convict someone. Ballistics can easily be challenged. If you have a gun that matches both the firing pin markings and barrel markings on fired ammunition, and if you have motive, no alibi and there are witnesses that place you at the scene then yes it is helpful evidence.

Answer 3

Yes, firing pins leave a distinctive mark as well as the bolt face and chamber scratches from extracting from the chamber.

Magazines can leave distinctive marks too.