9mm vs .40 S&W (2026): Recoil, Capacity, Ballistics & Which to Choose
9mm and 40 S&W have competed for decades as defensive handgun calibers. Modern ballistics have shifted the debate—here's what you need to know to make an informed choice.
9mm vs .40 S&W: What Actually Matters for Self-Defense
Whether you're choosing a caliber for concealed carry, home defense, or duty use, understanding the real differences between 9mm and .40 S&W helps you make an informed decision. The FBI announced a return to 9mm duty ammo in 2015 after decades of .40 S&W use, signaling an important shift. Modern 9mm ammunition with improved bullet technology performs nearly identically to .40 S&W in FBI testing, while offering higher capacity, less recoil, and faster follow-up shots.
Quick Answer
For most people, 9mm is the better pick because it's easier to shoot well, holds more rounds, and costs less to practice with. Choose .40 S&W if you already own it, shoot it equally well, or have a specific duty requirement.
Ballistic Performance
Penetration: With modern defensive ammunition, both calibers can meet the FBI's commonly cited 12–18 inch penetration window in calibrated 10% gel when using quality duty-style JHPs—meeting the standard for reliable incapacitation.
Expansion: Quality hollow points in both calibers often expand reliably in the ~0.55–0.75 inch range in gel depending on the load and test conditions.
Energy: .40 S&W often carries more energy, but with modern JHP design, real-world terminal performance differences are usually small compared with shot placement and ability to shoot fast/accurately. For example, many common duty-style loads cluster around ~400 ft-lbs at the muzzle.
Practical Considerations
Capacity: In the same handgun model, 9mm usually holds +1 to +3 rounds versus .40 S&W. In a defensive situation, more rounds matter more than slightly more energy per round.
Recoil: 9mm's milder recoil allows faster, more accurate follow-up shots. Most shooters shoot 9mm significantly better than .40 S&W.
Cost: 9mm is usually cheaper for practice ammo, which typically means more training for the same budget.
Who Should Choose .40 S&W?
- Law enforcement required to carry it
- Shooters with existing .40 S&W pistols and ammo stocks
- Those who shoot .40 S&W as well as 9mm
Who Should Choose 9mm?
- Most shooters seeking optimal defensive performance
- Those prioritizing capacity and controllability
- Budget-conscious shooters
- Anyone building a new carry setup
Verdict
For most shooters, 9mm is the better choice in 2026. Modern ammunition has eliminated the performance gap while maintaining 9mm's advantages in capacity, recoil, and cost. Unless you have a specific reason to choose .40 S&W, go with 9mm.
9mm vs .40 S&W FAQ
Is .40 S&W "more stopping power" than 9mm?
Not in any meaningful way with modern ammunition. While .40 S&W typically delivers more muzzle energy, many agency evaluations and gel-testing results suggest that quality 9mm defensive loads perform nearly identically in terminal ballistics. Shot placement, capacity, and your ability to shoot accurately matter far more than the small energy difference.
Is 9mm better for new shooters?
Yes, generally. 9mm's milder recoil makes it easier to learn proper shooting fundamentals, allows faster follow-up shots, and reduces flinching. Most new shooters will shoot 9mm more accurately and confidently than .40 S&W, which translates to better defensive performance.
Is .40 S&W cheaper now because it's less popular?
Sometimes, but not consistently. While .40 S&W demand has decreased since the FBI's switch, prices haven't dropped dramatically. 9mm remains cheaper overall due to higher production volume and better economies of scale. You may find occasional .40 S&W deals, but 9mm is consistently more affordable for practice.
What matters more: energy or shot placement?
Shot placement matters far more. A well-placed 9mm round is more effective than a poorly placed .40 S&W. Many trainers and agency evaluations emphasize that with modern defensive ammunition, the small energy difference between 9mm and .40 S&W is negligible compared to your ability to place shots accurately and quickly.