"Forensic science has advanced to the point that PROVES the fired case will consistantly be the same from an individual gun."
No real disrespect intended, but perhaps you've been watching too much CSI.
1. Each cylinder in a revolver will have different tooling marks, which change over time (due to repeated loading, firing, and cleaning)
2. Cartridges are handled differently before inserting into cylinders. Some may be new and smooth, others may have rolled around in the glove box of a truck for 10 years.
3. Consider the number of revolvers owned in America, then compare to that the number actually used in a crime.
4. Only a few (newer) guns have had this fired case requirement.
5. Only a few locations actually collect these once-fired cases. Since there is only one case, how are other areas going to get the case information to do something with it? If there is a crime, is someone going to call another district and request all the once-fired cases that they have?
6. A revolver-shooting criminal would have to be below moronic to shoot someone and then intentionally dump their cases on the ground to be found. Maybe the gun could be found with the cases still in it, but even if that is true, you have 1-5 to deal with.
This pseudo scientific stuff just doesn't stand up when thought about for a couple of minutes. I would be VERY surprised if a single criminal case is ever really solved based on a once-fired case. If that's the best evidence that someone has on me, even a rookie lawyer better be able to get me off.