The 9mm vs. 40S&W: Which is Better?

The .40 caliber was an answer to a question that was quickly answered, and the answer is not .40 S&W. Plain and simple. Modern projectile technology solved a lot of issues formerly experienced with older duty caliber handgun loads, and has improved terminal performance overall. Once ammunition manufacturers started understanding the basic formula for designing reliable expanding handgun bullets, the caliber debate among duty calibers ultimately died.

Considering the studies and work of wound ballistics from Dr. Martin Fackler, the International Wound Ballistic Association and the FBI, ammunition companies began focusing more on weight retention, controlled expansion and delivering the most weight to vital organs, which means optimal penetration. In accordance with the FBI, "12-18 inches of penetration" is optimal performance for handgun projectiles. This is the criteria that most credible ammunition companies design their defensive ammunition to today.

When the .40 S&W and .357 SIG were introduced, consistent performing 9mm Parabellum options were really few and far between. Even Winchesters SXT/Black Talon (what I often call, the "grandfather of modern bullet performance") was still in its infancy. Many poor performers existed on the market. The infamous "Silvertip" 115-grain from Winchester (see Miami 1986 shootout) and Federal Hi-Shok 115-grain were among some common ammunition offerings at this time. Both cartridges were considered poor performers in roughly every aspect, especially in terms of FBI protocol. The .40 S&W gave a larger diameter projectile compared to the 9mm Parabellum and higher magazine capacity and velocity over the .45 ACP. It also provided lower felt recoil than the 10mm Auto. At this time, the .40 S&W and .357 SIG both seemed like a good fit for defensive use.

While it is true that surface area delivered to vital organs can provide more disruption of vitals, it is also true the 9mm Parabellum’s velocity advantage provides consistently higher velocities, meaning the 9mm has a higher probability of consistent expansion when interacting in various densities and light barriers (such as heavy clothing, an FBI test protocol). This, coupled with modern ammunition capabilities and performance, means duty calibers are on a practically even playing field (with slight advantages and disadvantages between calibers) when it comes to terminal performance.

Basically, modern expanding 9mm projectile designs provide reliable expansion and the desired level of penetration. The result is terminal performance on par with similar modern .40 S&W loads. In addition though, in similar size and weight firearms, the 9mm Parabellum will exhibit less felt recoil. This makes for a more comfortable and easier to shoot handgun, and reduced split times between shots. The 9mm Parabellum also holds an advantage when it comes to magazine capacity over the .40 S&W. So, today the 9mm Parabellum has on par terminal performance, less felt recoil and holds more cartridges in a similar-size platform compared to mid-bore .40 S&W.

In the end, caliber should be the least of a user’s concern. Shot placement, recoil mitigation, shot consistency, capacity, ability and training should be higher on a user’s list. Is the .40 S&W dead? Not really. It is a caliber designed to fix a problem that technology ultimately fixed. If it wasn’t for Police Departments and Government agencies jumping on the .40 caliber bandwagon back in the day, it would likely be a more obscure caliber today, like the .41 Magnum. So, if given the option I’d pick a 9mm Parabellum over a .40 S&W today.

If you have any thoughts or comments on this article, we’d love to hear them. Email us at FirearmsNews@Outdoorsg.com.

About the Author:

Michelle Hamilton has a Bachelor’s degree in Criminal Justice/Homeland Security, is a serious student of military history, small arms design and manufacturing and is a competitive shooter.