Brady & Calif hearings on microstamping
Brady Campaign rejoices that a proposal for gun microstamping (putting tiny engravings on the firing pin to mark cartridges fired from the gun) has been shown to function.
Of course, the real issue is how little effort is required to defeat the measure. With a .45 and a spare firing pin, I'd say about 2-3 minutes. If they microstamp the bolt face, then it'd take a spare slide and about 45 seconds. And if you can't get the spare parts, I suspect a 15 second pass with a Dremel mototool would do the job.
[UPDATE: Refugee notes in comments that a legislator says they had a guy remove 70 microns from the firing pin tip and the marking were still visible. I've hunted around to get an idea of whether 70 microns is significant enough to where removing more would cause a malfunction. It doesn't look that way. This webpage on the Steyr Scout says factory tolerances for firing pin protrusion are ".050" - .059" (1.3 mm – 1.5 mm)." This military manual indicates that for an M-1 tolerances are broader: "The minimum should be 0.044 inch and the maximum should be 0.0590 inch." And here's an exchange about the Remington 700, saying tolerances are .055-.060," and he used .052" but had some misfires.
I haven't found the specs for handguns, but these would indicate that the tolerances in question are at least about .2 mm, and at most over 1mm (.05"). Since a micron is a thousandth of a millimeter, seventy of them would be .07 mm. This suggests that the amount removed in the test is far less than factory tolerances would allow, let alone how far it can be taken before the gun malfunctions. You might be able to take 3-10x that much off without going out of tolerance]