He is talking about micro stamping ammunition with a serial number. So far I think CA is the only state to vote for such BS. I may be wrong.
I think you’re confusing “micro-stamping” and “Ammo coding”.
Microstamping involves etching a serial number on the firing pin and chamber wall to imprint on the case when fired. Only meaningful for semi-autos, which eject cases. California may have passed such a law, to take effect in 2010.
Ammocoding involves etching a serial number on the base of the bullet. Legislation mandating that has been introduced in twenty-or-so states, but has gone nowhere, to the best of my knowledge. Articles on this can be found by checking FR keyword “ammocoding”.