Forensic Ballistics, ballistic fingerprints, and firearm microstamping

Today I looked at forensic ballistics which is the study of finding a bullet or cartrige and using the markings on it to trace the gun that shot it. How guns work in a nutshell is that a firing pin hits the cartriage at a place called the primer which causes an explosion that heats the powder and shoots the bullet. The central concept of forensic ballistics is that all guns leave distint markings on the cartriages, like fingerprints for humans. New York and Maryland have taken the leap to require all new guns to have a record of its cartraige markings, but it has yet to solve a single crime. Plus it is very easy to change the markings using household tools or you could simply change the parts of the firearm to make separate marks. Only 120,000 ballistic finger prints have been recorded out of 200 million which is less than 1 %, so ballistic fingerprinting may not be the best method of obtaining evidence. Another method that we might look forward to in the future might be firearm microstamping which is where a small ingraving is placed on the firing pin,ejector,barrel etc to make tracing the gun more practical. But this is a very contraversial method because some gun owners may feel an invasion of privacy.