Some states want micro stamping on the firing pin so it's imprinted on the fired casing. Another feel good gimmick that won't do anything.
The firing pin already micro stamps the primer of every cartridge you fire.
The tooling marks on every firing pin are as unique as a fingerprint, on a microscopic level.
As for serializing the base of a projectile, there are plenty of reasons to oppose that. But the cost to the major manufactures isn't one of them. Adding a laser marking system to a production line is relatively cheap and easy. As with any .gov regulation, it would be a tough pill to swallow for the little guys.