The 9mm and the 0.40 S&W provide nearly identical accuracy, drift and drop, but the 0.40 S&W has an energy advantage. The .40 S&W was designed such that it could be retrofitted into medium-frame (9mm size) automatic handguns. So most .40 caliber handguns can be easily converted to 9mm for cheaper target shooting with a simple barrel and magazine swap. However, case failure rates are higher when the 0.40 S&W cartridge is adapted for narrower frames meant for the 9mm. The 9mm and the .40 S&W (Smith and Wesson), along with the 0.45 ACP are among the most popular rimless cartridges for handguns.
The 9mm cartridge was designed by Georg Luger in 1901. It has been produced since 1902.
The .40 cartridge was designed by Smith & Wesson in 1990.
edit Evolution and Usage
The 9mm cartridge was developed from Luger’s 7.65x21mm Parabellum. The bottleneck of that cartridge was removed, leaving a tapered, rimless cartridge. It was adopted by the German Navy in 1904 and the German Army in 1906. It became more popular after World War I and has since become the most common caliber for U.S. law enforcement agencies and for military and law enforcement agencies around the world. It is also popular for self-defense.
The .40 cartridge was developed to the specifications of the FBI, which requested a gun that could reliably function while firing 10mm ammunition. Smith & Wesson realized that a new cartridge using a small pistol primer would be more effective.
edit For Home Defense
This video compares the 9mm with the 40 SW for their applications in home defense.
The 9mm has a bullet diameter of 9.01mm (0.355 in), a neck diameter of 9.65mm, a base diameter of 9.93 mm, a rim diameter of 9.96mm and a rim thickness of 0.90 mm.
The .40 has a bullet diameter of 10.2mm (.400 in), a neck diameter of 10.7mm, a shoulder diameter of 10.7 mm, a base diameter of 10.8mm, a rim diameter of 10.8mm and a rim thickness of 1.4mm.
edit Magazine capacity
Due to the smaller size of the bullet, 9mm guns typically have a higher magazine capacity than a .40, although the specifics vary depending on the type of gun. For example, the Beretta 92 gun holds 15 rounds of 9mm bullets, while the Beretta 96 holds 12 rounds of .40 bullets. Similarly, the Glock 17 holds a standard 17 rounds of 9mm bullets, while the Glock 22 holds a standard 15 rounds of .40 bullets.
The 9mm and the .40 have almost identical accuracy, drift and drop. In other words, the bullets act similarly in the air, and drift sideways, drop in height and hit targets at a similar rate after being shot.
A 9mm fires bullets with a velocity of between 990 and 1400 feet per second.
A .40 fires bullets with a velocity between 950 and 1440 feet per second, depending on the model.
A 9mm averages between 8” and 15.9” penetration. However, the Winchester FMJ has a penetration of 24.5” and the Doubletap JFN+P trail defense has a penetration of 40”. The cartridge expands to approximately 0.35” to 0.72”.
A typical .40 SW averages between 9.8” and 13.3” penetration. The Winchester FMJ, however, has a penetration of 25”. It expands to between 0.4” and 0.76”.
This video compares the penetration for 0.40 S&W and 9mm bullets:
9mm cartridges are the most popular and common cartridges in the world. They are the predominant cartridge used by United States enforcement agencies. They are also used by individuals for self defense.
.40 cartridges are also popular with law enforcement agencies in the United States, Canada and Australia. They have been called “the ideal cartridge for personal defense and law enforcement.”