I Have a Dumb Question About Gun Crime (opens in new tab)

(a) TV shows are not a good source of information about criminal ballistics; and

(b) every round that is fired, and every scratch inflicted in cleaning the gun, can change the pattern left on the bullet.

(c) see "microtaggants" and the suggestions that they be required in all ammunition. This is far closer to what you want but then we just have to steal ammo we want to use for nefarious purpose.

Interesting question.. I believe it is down only in the US according to the original-original article. Other countries still solve the crimes at a very high rate. Second, in US, the ballistics records are not searchable. Federal government is prohibited from creating a national registry and while ATF has some records of guns, esp. from out of business dealers, it is not a searchable database. Third, not every bullet carries a clean indication of the gun which it was fired from. Depending on what stopped the bullet, it makes up for a large amount of guesswork. So, guns make the crime much harder to solve.

According to a CBS News story, murder clearance rates for white and Hispanic victims continued to increase until 2019, but the clearance rate for black victims peaked in 1998 https://www.cbsnews.com/news/unsolved-murders-crime-without-....