For anyone who knows...do cartridges fired from an AK-47 display a distinctive impression that can be traced back to the firing gun? Like a pistol?
to answer your question, to a degree, yes. A case fired from a gun leaves a “fingerprint” allowing a match to be attained. However, unlike real fingerprints, the more a gun is used, the more the chamber, firing pin impression and rifling change.
This means that the first bullet fired from a gun will have different markings due to wear than say the 500th or 5000th round. The cases will bear different markings as well.
If the barrel is lapped, the markings on the lands and grooves will show a different pattern than before the lapping.
Firearms forensics is a fickle science depending upon the suspect weapon having not been modified or shot all to hell before recovery.
Yes, it seems possible to trace any fired bullet to the firing arm by matching the marks on the bullet to a bullet fired by the arm. As you can imagine, it would be very difficult to perform the match if the arm is not readily available for testing and bullet comparison. In a criminal investigation, the arm and fired bullets are usually easy to connect but if there were hundreds of arms at the crime scene, it would not be so easy. Someone correct me if I am wrong—I am not an expert in crime forensics.
If I were trying to set up a tracing program to follow illegal arms to a crime organization, I would think that microstamping (or other marking of the arms) would be an important technique to use so that the bullets/cases could be easily identified to the firing arm.