.40 S&W: The Law Enforcement Round That Bridged the Gap
The .40 S&W (Smith & Wesson) cartridge was born out of necessity—and controversy. In the aftermath of the 1986 FBI Miami shootout, where agents armed with 9mm pistols and .38 Special revolvers were outgunned, the agency began searching for a more effective handgun caliber with stopping power. Their initial solution was the hard-hitting 10mm Auto, but it quickly became clear that 10mm’s high recoil and large frame pistols were too much for many agents to handle.
Enter the .40 Smith & Wesson, introduced in 1990 through a collaboration between Smith & Wesson and Winchester. Designed to replicate the FBI's reduced-recoil 10mm load in a shorter case, the .40 S&W could fit in 9mm-sized frames—offering the power the agency wanted in a more manageable platform.
The result was a round that delivered more energy than 9mm, with better magazine capacity than .45 ACP. Law enforcement across the U.S. quickly adopted the .40 S&W pistol, making it the duty weapon standard for nearly two decades. Agencies valued its balance between capacity, recoil, and stopping power.
While some departments have since returned to modern 9mm loads—citing improvements in hollow point technology and lower training costs—the .40 S&W still holds strong with many shooters. It's often chosen by those who want a powerful self-defense round without stepping up to full-size 10mm recoil.
Modern .40 S&W ammo includes everything from soft-shooting target loads to bonded jacketed hollow points designed for deep penetration and expansion. The best .40 caliber ammo for self-defense is now highly refined, giving users peace of mind whether they carry daily or keep a pistol for home protection.
Popular handguns chambered in .40 S&W include the Glock 22 and 23, Smith & Wesson M&P40, SIG Sauer P229, and H&K USP Compact. Many of these platforms are trusted by professionals and civilians alike.
Though its heyday may have passed in the law enforcement world, the .40 S&W still offers an excellent option for shooters who want more punch than 9mm but less recoil than 10mm. It remains a versatile, respected cartridge with a proven track record in defense and duty.
