And let me guess, there's an exception for firearms purchased by police right? The goal of microstamping isn't to help solve crimes, it's to make the manufacture of firearms so costly that people cannot afford them and/or a manufacturer will decide to abandon an entire market before even trying.
If S&W is abandoning California, which I applaud, then that should also include abandonment of any government contracts there. Don't sell anything to the Only Ones, don't service any existing equipment. Tell them they can do their jobs with a cell phone and a rape whistle since that's what they expect of the citizenry.
Some gun companies have already adopted a policy of treating police departments by the same rules citizens in that state are subject to, i.e. not supplying firearms that are banned for private citizens. This needs to happen more.