Here is the report from the Calif. DOJ about ballistic finger printing.
http://www.nssf.org/PDF/CA_study.pdf
In short it says it is useful to identify if the same gun was used in different crimes, but when the population is expanded to include every gun in the state the chance of a match is pretty dismal because of the similarities of markings from using the same tooling. The DOJ determined the cost would outweigh the benefits.
Exactly what my point has been. That while it is an extra tool, that helps when you have already narrowed down possibilites, it is not effective on a large scale. I don't know why a couple people are so adamant otherwise.
California hates guns, if they felt it was effective they would have implemented it if they could show even remotely it was useful when dealing with millions of guns.
The truth is it is really only good if you think you found a gun used in a specific crime you know about, and then test it to see if it is a match. If it doesn't match it does not even mean it was not the gun. Yet as the study showed so many will be flagged by the database as matches that need to be manualy examined that it renders it ineffective on a large scale. Essentialy it just allows you a fishing expedition to take a closer look at the owners of the flagged guns and determine who is suspicious. If you finaly do pinpoint a gun, a large majority of guns used in crimes are stolen so all that manpower has simply led you to a victim. The criminal that stole the gun from him probably sold it on the black market for money for some sort of drug like most burglaries are commited for. If somehow they finaly do track the gun down and it happens to be a match still, criminals share guns and sell guns as well so the suspicious scumbag you are lead to is still not proof of his involvement in the crime.
So then the investigation would switch to trying to find connections and ties with people who may or may not even be connected. If you somehow do find a connection and it points to some little ghetto full of gangs and crime where guns change hands between addicts and gangsters frequently the person found with the gun simply having a connection to the crime or victim in a small area does not necessarily mean it was him. Of course at that point a prosecutor wouldn't care and would be searching for motive. You might take scum off the streets but it wouldn't necessarily even be the right one.
So even when it does work it doesn't pan out for the most common types of murders. Plus it would be a sad day when polishing or weatherproofing your gun is suspicious because it changed the 'fingerprint' the gun makes on the casing. Perhaps every barrel sold needs fingerprinting? Or maybe every breech and firing pin and ejector and barrel needs to be seperately serial numbered so you can try to track when each was in a certain gun and at which point it was polished, weatherproofed, changed to improve performance etc.
Or maybe, just maybe it is a waste of taxpayer money and an extra infringement on gun owners who would get no knock raids when stolen guns, privately transfered guns, guns similar enough to thiers are traced. Since you have to manualy inspect the firearm that would mean a lot of warrants for all those thousands of computer flagged possibilites for every crime.
LEO will soothe you by saying "Oh don't worry they would probably no knock swat raid the more suspicious on the list first. Your past is squeeky clean right?"