When choosing any product, weighing the pros and cons is essential. For a handgun, it's crucial to test the caliber, carry style, fit, sights, and weight before purchase.

Many initial purchasers go with the "tried and true" handgun staples, such as Glock or Sig Sauer. Despite the insistence of some firearm enthusiasts, there is no "best" brand. While you can spend hours reading brand forums, most handgun purchases come down to personal preference.

Preference matters, but the caliber should play the most significant role in your purchase. It is essential to consider some critical factors in the ammo options available to you. In this article, we’ll compare two top choices commonly used within the military and law enforcement: the .40 S&W and the 9mm Luger.

The .40 S&W vs. the 9mm Luger

The .40 S&W and the 9mm Luger calibers offer a wide range of shooting platforms. However, the 9mm round is the most popular in today's modern-era handguns. While the 9mm was initially developed in WWI to penetrate through field gear, it has held up through the tests of time.

The .40 S&W is considered a mix between the 9mm and .45 ACP, originally designed and developed for law enforcement use following the 1986 FBI Miami shootout. Smith & Wesson aimed to create something similar to the ballistics of the 10mm cartridge but with a greater capacity than larger calibers allowed.

Penetration and Stopping Power

With a wide range of ammunition options, the 9mm can vary in penetrative performance but generally scores high. In most testing, the .40 S&W is more impact-oriented and stops between a narrow range of inches.

Some consider bullet penetration beneficial. Others cite the potential risks of a highly penetrative round, especially when considering loved ones in home defense scenarios. Nevertheless, the penetration issue isn't as concerning as a round's "stopping power."

Some shooters claim stopping power is a myth. From any standard viewpoint, this might be the case. It's hard to measure levels of incapacitation on an assailant, and the data on the subject generally remains inconclusive.

The term "knockdown power," which many refer to when discussing big-caliber handguns and revolvers, is ungrounded. When comparing ammunition, know that there is an equal chance that the assailant won't stop their attack, even when hit.

The ballistics and specs of a caliber don't equate to stopping power. Therefore, stopping power shouldn't play a role in your choice of handgun. For an effective result, your goal should be to find the target and hit it dead-on.

Recoil Management and Follow-Up Shot

Experienced shooters are confident with any handgun and caliber. However, new shooters must choose a caliber that is easy to control and keep the sights aligned.

Regarding recoil management, the 9mm is the apparent winner. There's no denying that forty-caliber rounds have a more noticeable, "snappy" recoil.

However, if you have a firm enough grip to control the recoil and are willing to invest time in practice so you don't develop a flinch, the .40 S&W might be the better round for you. In this case, a higher-weighted pistol will help tame the recoil.

The preference for shooters with smaller physical frames is 9mm, as gun control is more manageable through the wrist. The felt recoil in the 9mm is more muted than the .40. This is especially important in concealed models that are small and designed for inconspicuous carry.

For most shooters, recoil management and follow-up shots are paramount. When engaged in a tense situation, more rounds in a tighter grouping on the main target are vital in neutralizing a threat.

Magazine capacity does matter! Especially when dealing with the possibility of multiple attackers, the ability for more follow-up shots is paramount. With terminal ballistics remaining functionally the same, a shooter can carry more 9mm rounds than .40.

Cost Effectiveness and Availability

The price between the two calibers isn't significantly different in small amounts of ammunition. However, the price gap becomes visible if the intent is to shoot hundreds of rounds monthly.

In this case, the 9 mm Luger has the better cost per round and gives a broader range of choices. Unfortunately, 9mm ammunition becomes even more scarce in times of short supply.

The next topic is that of availability. The majority of gun enthusiasts own at least one 9mm handgun. Because of this, the 9mm Luger is widely available and inexpensive in seasons of ample supply. In short supply, costs skyrocket.

The .40 S&W isn't immune to scarcity issues, but it tends to be easier to find online and on store shelves—especially when needed in a pinch. Since fewer people own .40 caliber handguns, ammunition is more widely available due to fewer buy-ups.

While this shouldn't be a primary factor in your handgun purchase, it is something to consider. Cost is a non-issue, especially when .223 alternatives are astronomically more expensive. Likewise, scarcity problems are generally short-lived.

How to choose: .40 S&W vs. 9mm Luger

As with many things, there isn't a "right answer" in this discussion. The popularity, limited recoil, and concealed-carry use for the 9mm Luger certainly speak to its dominance in the space. It is the clear choice for many shooters, but not for all.

The .40 S&W provides some objective differences that can improve the shooter while ensuring the same goals are completed as with the 9mm. It is popular in law enforcement and home-defense situations due to its impact-oriented penetration.

The best recommendation is to shoot both calibers to find the best "fit" for your preferences. Focus on the task at hand and ask yourself:

• Can I get rounds on the target in a tight grouping?
• Can I do it quickly, without adjusting my aim or sight?
• Does the bullet make the intended impact?

If you can answer yes to these basic questions, it is the right caliber choice for you.