I have it on good authority that any time there is a shooting, the gun is confiscated for "testing". Whatever that testing is can can be, you can bet that it is compared to models that come out of the factories.

Many years ago, I traded some handloaded .45 ACP ammo to a fellow that somehow ended up with shooting himself in the foot. His pistol was taken by the cops, kept for some three months, "tested" and he was billed for close to $150 for the "testing" before the gun was returned. It was never explained to his satisfaction what "testing" the gun underwent.