This is why you always leave the gun and take the cannoli.
It’s extremely uncommon for a usable fingerprint to be obtained from a pistol. While it is apparently scientifically possible to obtain a fingerprint from a spent casing, the number of times it’s actually happened seem negligible.
I would have thought that simply wearing surgical latex gloves would defeat the gunpowder residue test. However, I think one Law and Order* episode, they also ran he test on the clothes (if you fire near your clothing).
Plus, L&O also seemed to suggest the impression left by the firing pin was distinctive enough to help rule a gun out or in. If it’s a hot gun, it’s possible you don’t know where that gun has been and what it was up to.
Something I read said that firing several dozen rounds (about 100 or more?) would significantly alter the rifling marks a gun leaves on bullets. Filing the barrel would leave obvious damage. Firing a lot would likely not leave evidence.
*Our font of knowledge for all things legal and forensic.
A firing pin, extractor, or ejector marking would help identify the make of the firearm in question. As in “Aha! This shell casing came out of a Colt Government Model M-1911a1 in .45 ACP.” The striations on the bullet can match a particular firearm to a bullet. So all they have to do is track down every Colt M-1911a1 and fire a test bullet through them. They’ve been making them for what, 102 years now?
Best bet is to lose the gun. Or replace the barrel with a new one before you commit a crime, then put the old one back and lose the new barrel. I’ve heard washing your hands with comet cleanser can quickly take care of residue on your hands.