There was both a very effective team of Mafia killers in the 1970s, who were known as the “.22 caliber hitters”. They were believed responsible for some 20 killings since 1976, and were never arrested for those crimes.
Likewise, Joseph Christopher, a psychotic racist and serial killer, was known as the “.22 caliber killer”, and over the course of a single year, he was believed to have killed at least twelve, and wounded numerous others. He was a US Army infantry private at the time.
Yes, it is not a big round.
The names Principe and Gallina sounded familiar but I had forgotten the story.