9mm vs .40 S&W: A Comparison

9mm vs .40 S&W: A Comparison

Hey all, we here at True Shot Academy are going to talk about two of the most prevalent defensive handgun cartridges today. The 9mm Luger (also called 9mm Parabellum, 9x19mm, 9mm NATO, or simply 9mm) and .40 Smith & Wesson (often simply called .40 S&W) represent different approaches to the ideal defensive pistol caliber, each with passionate advocates within law enforcement and civilian shooting communities. Today we will compare these two influential cartridges across ballistic performance, practical applications, and real-world considerations. Without further ado, let's examine these two defensive pistol champions.

9mm and .40 S&W Background

The 9mm Luger emerged in 1902, designed by German firearms engineer Georg Luger for his iconic toggle-action pistol. Adopted by the German military in 1908, the cartridge spread globally throughout both World Wars, becoming the most widely used military handgun cartridge in the world. Despite its early development, the 9mm didn't achieve widespread American law enforcement adoption until the 1980s, when the FBI and other agencies began transitioning from revolvers to semi-automatic pistols with higher capacity. The .40 S&W followed a dramatically different development path, arriving nearly 90 years after the 9mm. Developed jointly by Smith & Wesson and Winchester in 1990, the cartridge emerged directly from the FBI's perceived need for a more effective round following the infamous 1986 Miami shootout where their 9mm service ammunition performed inadequately. The .40 S&W essentially repackaged the ballistics of the 10mm Auto (which the FBI had briefly adopted but found too powerful for many agents) into a shorter case that could function in medium-frame pistols designed originally for 9mm. These different origins reflect the cartridges' distinct design philosophies. The 9mm prioritizes capacity, moderate recoil, and controllability, while the .40 S&W emphasizes enhanced terminal performance and energy transfer at the cost of reduced capacity and increased recoil. This fundamental difference has shaped the decades-long debate between advocates of both cartridges.

Cartridge Specifications and Physical Characteristics

These cartridges differ significantly in their physical dimensions despite often appearing in similarly sized firearms. The 9mm features a tapered, rimless case measuring 19mm in length with a case mouth diameter of 9.93mm. It fires .355" diameter bullets typically weighing between 115 and 147 grains, with 115, 124, and 147 grains being the most common commercial loadings. The cartridge operates at a SAAMI maximum pressure of 35,000 psi. The .40 S&W utilizes a slightly larger case measuring 21.6mm in length with straighter walls and a case mouth diameter of 10.77mm. It fires .400" diameter bullets typically weighing between 135 and 180 grains, with 155, 165, and 180 grains representing the most common weights. The cartridge operates at a slightly higher 35,000 psi maximum pressure but generates significantly more energy due to its larger diameter and heavier bullets. These dimensional differences directly impact magazine capacity in similarly sized firearms. A full-size service pistol that holds 17-18 rounds of 9mm will typically accommodate only 14-15 rounds of .40 S&W. This capacity differential represents one of the most practical distinctions between these cartridges in defensive applications. Purchase 9mm Ammo

Ballistic Performance Comparison

The ballistic profiles of these cartridges reveal significant performance differences despite their similar pressure ratings. The 9mm typically propels a 124-grain bullet at approximately 1,150 fps from a 4-inch barrel, generating around 365 foot-pounds of energy. Lighter 115-grain bullets often achieve 1,180-1,250 fps, while heavier 147-grain subsonic loads travel at 950-1,000 fps. Modern +P loads increase these figures by roughly 10%, with some +P+ offerings approaching the ballistics of much larger cartridges, though at higher pressure levels. By comparison, the .40 S&W drives a 165-grain bullet at approximately 1,130 fps from the same barrel length, producing about 470 foot-pounds of energy—nearly 30% more than standard 9mm loads. Lighter 135-140 grain bullets can exceed 1,200 fps, while heavier 180-grain projectiles typically travel at 1,000-1,050 fps. Even standard-pressure .40 S&W loads deliver energy levels comparable to 9mm +P ammunition. Terminal performance differences have narrowed considerably with modern defensive ammunition. Contemporary hollow point designs from major manufacturers perform reliably in both calibers, typically expanding to similar diameters despite their different initial bullet sizes. The .40 S&W maintains advantages in momentum and energy transfer, while the 9mm often delivers superior penetration depth due to its higher sectional density with certain bullet designs.

Available Ammunition Types

Both cartridges come in diverse loadings designed for specific applications: 9mm Varieties:

• Full Metal Jacket (FMJ): Widely available practice ammunition in weights from 115-147 grains
• Jacketed Hollow Point (JHP): Extensive options from virtually every manufacturer with various expansion and penetration characteristics
• +P and +P+ Loadings: Higher-pressure variants providing enhanced velocity and energy
• Frangible: Training-specific loads designed to disintegrate on impact with hard surfaces
• Subsonic: Specifically designed for suppressed applications, typically using 147+ grain bullets

40 S&W Varieties:

• Full Metal Jacket (FMJ): Practice and training loads typically in 165-180 grain weights
• Jacketed Hollow Point (JHP): Defensive-oriented expanding bullets optimized for terminal performance
• Reduced Recoil: Specialized loadings designed to approximate 9mm recoil levels while maintaining adequate terminal performance
• Specialty Defensive: Various proprietary designs including fragmenting bullets, dual-projectile loads, and barrier-blind options
• Frangible and Training: Specialized options for law enforcement and high-volume users

The 9mm generally offers greater variety and typically costs 15-25% less than comparable .40 S&W ammunition. This cost difference becomes particularly significant for high-volume shooters or agencies with limited training budgets, potentially allowing more practice with the same financial resources.

Major Ammunition Manufacturers

Virtually every major ammunition manufacturer produces both cartridges: Federal offers extensive options in both calibers, from affordable American Eagle practice ammunition to premium HST and Hydra-Shok defensive loads. Their HST design has established itself as one of the most consistently performing hollow points in both calibers. Speer produces the renowned Gold Dot line, featuring bonded hollow points that deliver reliable expansion and weight retention. Their Lawman training ammunition provides economical options that duplicate the ballistics of their defensive loads at lower cost. Winchester manufactures numerous options including white box practice ammunition, Ranger-T law enforcement ammunition, and PDX1 defensive loads. Their Silvertip and Defend loads provide additional defensive options at various price points. Hornady offers Critical Defense and Critical Duty lines optimized for different barrier penetration requirements, along with Custom and American Gunner options for practice and general-purpose use. Sig Sauer's relatively recent entry into ammunition manufacturing focuses on optimized defensive loads in both calibers, with their V-Crown JHP and solid copper Elite Performance V-Crown bullets delivering consistent expansion. Specialized manufacturers like Underwood and Buffalo Bore produce high-performance loads that exceed standard factory velocities, while Federal HST, Speer Gold Dot, and Hornady Critical Duty dominate law enforcement contracts due to their consistent barrier penetration and terminal performance. Purchase .40 S&W Ammo

Firearms Chambered in 9mm and .40 S&W

Both cartridges appear in numerous firearms from virtually all major manufacturers: 9mm Firearms: Glock's Models 17, 19, 26, and 43 represent some of the most popular 9mm pistols worldwide, spanning from full-size to subcompact options. SIG Sauer's P320 and P365 series, Smith & Wesson's M&P line, HK's VP9 and P30, and CZ's P-10 and P-01 series offer extensive options across various operating systems and size categories. Beyond pistols, the 9mm appears in numerous pistol-caliber carbines including the CZ Scorpion, HK MP5, Ruger PC Carbine, and various AR-15 pattern PCCs that enhance the cartridge's ballistic performance through longer barrels. .40 S&W Firearms: The .40 S&W appears in many of the same platforms as 9mm, with Glock's Models 22, 23, and 27 representing .40 S&W versions of their popular 9mm offerings. Smith & Wesson's M&P40, SIG's P229 and P226, and HK's USP40 and P2000 provide quality options from major manufacturers. While still widely available, .40 S&W firearms have seen decreased production as law enforcement agencies trend back toward 9mm. Several manufacturers have reduced their .40 S&W offerings in recent years, though the cartridge maintains substantial market presence due to its large installed base and continued civilian popularity. Pistol-caliber carbines in .40 S&W exist but in smaller numbers than 9mm options, with the Kriss Vector, Just Right Carbines, and some specialized AR platforms being among the more common examples.

Practical Applications and Use Cases

These cartridges serve similar roles but with different strength profiles based on their performance characteristics: The 9mm excels in:

• Defensive applications where capacity and rapid follow-up shots take priority
• High-volume training where cost and controllability enhance skill development
• Compact and subcompact carry pistols where recoil management becomes critical
• Competition shooting where fast target transitions and ammunition cost impact performance

The .40 S&W performs best for:

• Scenarios demanding maximum energy transfer without moving to large-frame pistols
• Situations where barrier penetration and terminal performance take priority over capacity
• Users confident in their recoil management abilities who prefer larger bullets
• Applications where the ballistic middle-ground between 9mm and .45 ACP is desirable

The 9mm's resurgence in law enforcement—including the FBI's return to the caliber in 2015 after 25 years with .40 S&W—reflects advances in defensive ammunition that have narrowed the terminal performance gap while highlighting the 9mm's advantages in capacity, shootability, and service life of firearms.

Conclusion

The 9mm and .40 S&W represent different approaches to defensive handgun cartridge design, each with distinct advantages depending on user priorities and applications. The 9mm offers higher capacity, lower recoil, reduced ammunition cost, and excellent terminal performance with modern defensive loads. The .40 S&W delivers enhanced energy, larger diameter, and greater momentum while still functioning in medium-frame pistols at the cost of increased recoil and reduced capacity. Both cartridges continue to serve effectively in defensive roles, with selection often hinging on individual shooter preferences regarding the capacity-versus-power balance. The 9mm's recent resurgence in law enforcement suggests a shift toward prioritizing shot placement and capacity over raw power, though the .40 S&W maintains a substantial following among shooters who value its ballistic advantages. All in all, both cartridges offer proven effectiveness with modern defensive ammunition, making either a viable choice depending on shooter preference and intended application. We here at True Shot Ammo carry an extensive selection of both 9mm ammo and .40 S&W ammunition in addition to our inventory of ammo for sale. Our range of ammunition for sale encompasses popular calibers and gauges like 9mm, 5.56, 12 gauge, .22 LR. Whether you want to buy 9mm ammunition, buy .40 S&W ammo, or buy bulk ammo, we have got you covered. As always, happy shooting.