How a 1986 FBI shootout redesigned the modern handgun cartridge

Cultures · Published 1 October 2026 Swipe more like this →

In short: After a deadly 1986 ambush in Miami, the FBI realized their revolvers were obsolete. They needed a semi-automatic solution that balanced stopping power with manageable recoil. The result was a collaborative engineering feat that changed law enforcement ballistics for decades.

The catalyst for change was the 1986 FBI Miami shootout, which left two agents dead and five wounded. This tragedy prompted the FBI to move away from standard-issue revolvers toward semi-abilities, seeking the advantages of higher ammunition capacity and faster reloading. During testing, FBI Firearms Training Unit chief John Hall experimented with the 10mm Auto, finding that a reduced-velocity load—using a 170–180 grain bullet at 900–1,000 ft/s—delivered the necessary terminal performance without the punishing recoil of conventional 10mm ammunition.

To make this performance portable, Smith & Wesson and Winchester collaborated in 1990 to create the .40 S&W. The goal was to fit the 10mm's effectiveness into a medium-frame 9mm-sized handgun. By shortening the 10mm case to remove excess airspace, they created a cartridge that could utilize existing 9mm-sized frames while maintaining the ballistic punch of the FBI's preferred load. The cartridge officially debuted on January 17, 1990, alongside the Smith & Wesson Model 4006.

While the .40 S&W became a staple for agencies like the FBI—which officially adopted it in May 1997—its dominance eventually waned. The 1994 Federal Assault Weapons Ban, which limited magazine capacities to ten rounds, initially boosted the caliber's popularity as buyers sought higher energy in restricted capacities. However, by 2015, the FBI announced a return to 9mm, citing improved ballistic technology, better accuracy, and the fact that .4 .40 S&W rounds caused excessive wear on pistols and were harder for agents to control.

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