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Which Cartridge Reigns Supreme for Concealed Carry and Self-Defense: 40 S&W Vs. 45 ACP Vs. 9mm



When it comes to selecting a cartridge for concealed carry and self-defense, gun owners often find themselves debating the merits of 40 S&W, 45 ACP, and 9mm. Each cartridge has its own set of pros and cons, and there is no one-size-fits-all solution. However, the 9mm is the most popular worldwide, and there are several reasons why.

Physics and Math

To understand why the 9mm is so popular, it’s essential to understand some physics and math. A bigger, heavier bullet carrying more energy means a deeper and larger wound channel. More velocity equates to more energy, and energy is the benchmark by which we rate a bullet’s performance. To sum up this fast physics lesson: all things being equal, a larger, heavier bullet will penetrate deeper than a lighter one.


The 9mm cartridge is smaller and lighter than its competitors, which makes it easier to handle and shoot. The reduced recoil allows for faster follow-up shots and makes it easier for smaller-statured individuals to shoot accurately. It is also a popular cartridge among law enforcement agencies because it allows for faster target acquisition and better accuracy.

Increased Magazine Capacity

One of the significant advantages of the 9mm cartridge is its increased magazine capacity. Because of its smaller size, firearms chambered in 9mm can hold more rounds than those chambered in 40 S&W or 45 ACP. In a self-defense situation, having more rounds can mean the difference between life and death.

Ammunition Choices

The 9mm has a wide range of ammunition choices, from full metal jacket rounds for target practice to hollow-point rounds for self-defense. With so many options available, it’s easier for gun owners to find a round that fits their specific needs.

The Move to 9mm

The move to the 9mm was not an instant success, as the Illinois State Police learned. They were one of the first U.S. law enforcement agencies to adopt the 9mm in the Smith & Wesson Model 39. The standard-issue round was either 100- or 115-grain, standard velocity. The load was mediocre at best, but when they changed to 115-grain hollow-point +P+, those .380-inch bullets leaving the muzzle of their Model 39s at a velocity of 1,300 fps changed the game. The initial 9mm rounds at the time used by law enforcement did not yet reach the nine’s full potential.

The Military Experience with the 9mm

One of the issues the military experienced with the 9mm was dissatisfaction with the M9 pistol specifically and ammunition in general. It boiled down to a report compiled by the Center for Naval Analyses (CNA) and released in 2006 titled, “Soldier Perspectives on Small Arms in Combat.” The report detailed a formal independent review of soldier opinions of their small arms in combat situations. Survey participants included over 2,600 soldiers who had returned from Iraq or Afghanistan and who had engaged in a firefight using the weapons listed. The net result was that soldiers were least satisfied with the M9 compared to the other weapons and “the most frequent recommendations included weapons and ammunition with more stopping power/lethality; higher quality magazines for the M9, M4 and M16; more durable ammo belt links and drum systems for the M249; and reduced size and weight in the M16 and M249.”

Stopping Power

Call it lethality, stopping power or knock-down power, but there is no definitive answer when it comes to which cartridge reigns supreme for concealed carry and self-defense. However, the 9mm is a popular choice for the reasons mentioned above. The 40 S&W and 45 ACP also have their own advantages, such as greater stopping power and larger bullet sizes. Ultimately, the decision should come down to personal preference, as well as individual skill and experience with each cartridge. It’s important to choose a cartridge that you are comfortable shooting and that will serve its intended purpose effectively. It’s also essential to prioritize training and practice to ensure you can use your firearm safely and effectively in a self-defense situation.
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