I'm pretty sure the idea of a national BF system is pure political BS and the idea lacks technical merit, but I am neither a ballistics expert nor a criminal investigator. I'm a gun owner and a taxpayer. Frankly I am a lot more concerned with the cost than with any privacy issues - Cost of new guns and cost of maintaining the system.
If someone can present a proper business analysis shows that a national BF system would be worth the money and hassle, let them make their case and then it can be debated. The argument would boil down to how much it would cost per crime solved, and that would have to be weighed against spending the money on something else or deciding that the best course of action is to do nothing.
I'd rather have a recommendation made by technical experts in the BATF (such as they are) than by people who have no knowledge of the subject. They may be Keystone Kops or JBTs, but they can act independently from the politicians.
I think there's a lot of misunderstanding about what BF is all about. Obviously it's useful in individual cases where you have two bullets that you believe were fired from the same weapon at about the same time. The gun control fanatics are creating two misperceptions:
1) That every brand new gun produces a set of marks on cases and bullets that are sufficiently unique to distingush that from every other brand new gun, even ones made with all the same tooling, and
2) That guns keep that uniqueness throughout their existence. Never mind the obvious realities of wear, cleaning, and interchangeable parts.
In a rational discussion of the real world mechanics, their argument will fail. Let them make it. Our job is to not allow a knee-jerk decision to be made for political reasons. We know that even if sound reason shows the idea of a national BF system to be bogus, the antis will spew their usual crap about us being against common sense, etc.