It might help convict Barney Fife...

...but in the real world it's just ludicrous. Sierra Times has some comments on California's idea for bullet serialization:

Gun Owners of California understands that SB 357 is truly motivated by a subversive desire to see all guns removed from the citizens of California. What other reason could there be when the stated goals cannot be matched up to conclusive studies and actual realities prove the goals unrealistic. It has been long known, for it is not hidden, that gun control proponents seek any, every and all avenues of stifling legitimate firearm ownership in this state.