In the United States, aside from the mob’s use of Tommy-Guns, rifles, and sawed-off shotguns during times of open gangland warfare, mob hitmen of the organized criminal underworld, be they Italian, Jewish, Irish, etc., tended to use .32 and .38 caliber “revolvers” for assassinations.

This it’s not to say that other calibers weren’t used, but the .32 and .38 revolvers were preferred. Both had tremendous firepower and even if you didn’t strike a major organ, they caused tremendous damage upon impact.

The reasoning for this was simple. Revolvers are more dependable than automatics because the cylinders on revolvers don’t jam, whereas the clip and action on an automatic pistol has the potential to jam up. More than one assassination was botched over the years for this very reason.

This is not to say that automatics weren’t used, because they were. I imagine they utilized whatever weapon was on hand and available to carry out a murder contract. But the more savvy killers tended to prefer revolvers for the reasons I mentioned.

By the mid-1970s, the widespread use of .22 caliber “automatics” became a preferred weapon of choice (and almost a fad among mafiosi) because a “hollow point” .22 caliber “Long” bullet could also cause tremendous damage. A "hollow point" spreads wider upon impact. So although it was only a .22 caliber, upon entering the body, the bullet took on a larger and more jagged edge, with the small, light-weight bullet tending to ricochet around within the victims body. So although the bullet didn’t have the firepower and initial impact of, say, a .38 caliber or 9mm shell, the .22 caliber would tear up organs and muscles as it traveled around inside an intended victim.

Other added benefits (and major considerations for using .22s) was that they made less noise, the clips held more bullets, and the weapons were usually smaller and lighter to carry on your person, making them easier to conceal in public…with the Italian-made .22 caliber Beretta becoming a favorite.