File off the firing pin markings
Nope they wouldn't care and are most likely too stupid to figure it out anyhow
Use an alternate firing pin
Nope again too stupid and you expect them to be gunsmiths now?
Most criminals will never fire their gun before using it in a crime and therefore will never go to a gun range to fire their stolen gun anyhow to be able to even get close to brass at a range
Spread decoy "range pickup" casings at crime scene
see above
Use a revolver or rimfire handgun
They will still use .22's or revolvers just as much as before
Use one of the 7 zillion non-marked pistols already in circulation
possibly, but then again you think they are going to be smart enough to know how to look and see if it's a "microstamping" firearm anyhow? They won't care either way
Use a stolen gun that traces back to some jerk in OC
They will most likely use a stolen gun or one from a straw purchase because they most likely will have already started their rap sheet
Go on a rampage, shoot self, don't care
Yes, but that is not your average crook, they prefer not to die and just take advantage of their prey
Put small patches of duct tape on primer before shooting
First I doubt that it would set of the primer, second, once again you really expect them to know how it even works or what to look for?
Use new black market "clean" firing pins that trace back to the jerk in OC
They wouldn't take the time nor the trouble to do that
Use home-made brass catcher (duct tape and a ziplock with air holes)
Once again why would they care? They gun is most likely stolen anyhow
They will continue to use whatever weapon is at their disposal, if they don't have a knife they'll use a bat, pointy stick, rock, scissors, snake, or even a karaoke machine.
Shoot the pistol 10k times at the range to wear out the markings
Now that's just funny! THAT would be a criminal I would be scared of, because he would actually know how to shoot! What are you assuming they are independently wealthy and can afford the ammo and just do robberies for fun? 10,000 rounds of ammo ain't cheap my friend!
Use a pistol from Canada (yes they do have them!)
Only when the supply from the streets in the US dry up, but then there is always Mexico.
Most likely not, bat's aren't that cheap, a good pipe can be found at construction sites. Also they are kinda hard to conceal...
That costs money! And besides there are already a lot of criminals there as well, who do you think runs that state!
They would only leave if there was say a hurricane, that drove them away into neighboring states...
did I just write that out loud?!