Kevin noted the study showing 'ballistic fingerprinting' is BS

here; now Ahab notes the study showing that the claims for microstamping of ammo are also the product of the backside of a hyena.
Two different methods were designed to evaluate the ease with which lasermachined micro-characters could be intentionally defaced or obliterated. In the first method, the firing pin for an AMT “Backup” 380 Auto semi-automatic pistol was held perpendicular to a household sharpening stone and rubbed back and forth for 30 seconds. The second method involved placing the firing pin for a Sig Sauer P229 semi-automatic pistol on its side on an anvil and rolling it back and forth while lightly peening it with a ball peen hammer for 15 seconds. The firing pin was then stood on its base and the tip was peened for an additional 15 seconds.

…

Finally, both defacement/obliteration methods demonstrated that the microcharacters could easily be intentionally destroyed with the firing pin removed from the firearm.

Go over and read up when you can.