https://www.scientificamerican.com/article/the-field-of-firearms-forensics-is-flawed/

Bullet and rifling forensics is not based on science

A barrel is a barrel, and I think it highly unlikely that a mass-produced product leaving a unique fingerprint on something that’s been smushed into a completely different shape can be used as forensic evidence. Unless you know of it being scientifically proven, it is the domain of TV CSI.

Glocks are the Toyota Corolla of handguns. They are the preferred weapon of police departments and federal agencies the world over.

They, and many modern firearms, use a rotary hammer forged barrel with polygonal rifling that does not leave unique markings like traditional cut rifling.

Also, forensic ballistics are mostly bunk, like forensic bite marks.