9mm vs 40 S&W
9mm vs 40 S&W – Which Pistol Cartridge Is Better?
Comparing 9mm vs 40 S&W usually comes down to capacity and recoil versus bullet diameter. In simple terms, the 9mm Luger gives you more rounds in the same size pistol and softer recoil, while the 40 S&W pushes a wider, heavier bullet at the same maximum pressure.
Quick Verdict
- 9mm Luger: more capacity, softer recoil, lower cost per round
- 40 S&W: wider .40" bullet, heavier standard weights (165–180 gr)
- Same SAAMI maximum average pressure: 35,000 psi for both
Winner for most users: 9mm for most shooters; 40 S&W if you already own and shoot a 40 well.
Side-by-Side Specs
| Spec | 9mm Luger | 40 S&W |
|---|---|---|
| SAAMI MAP (transducer) | 35,000 psi | 35,000 psi |
| Case length (SAAMI chamber min.) | .754 in | .850 in |
| SAAMI standard issued | — | Feb 1, 1990 |
| GLOCK full-size capacity | 17 (G17) | 15 (G22) |
| Best For | Carry, range, new shooters | Owners of 40 S&W duty guns |
Why the FBI Went Back to 9mm
In a May 6, 2014 memo, the FBI Training Division concluded that modern 9mm Luger duty bullets were, under identical testing, outperforming most premium 40 S&W and .45 Auto loads it tested, while offering higher capacity, less recoil and lower cost. FBI shooters were also faster and more accurate with 9mm in similar-size pistols. The Bureau then moved back to 9mm.
Capacity and Recoil
Because the 40 S&W case is wider, the same frame holds fewer rounds. GLOCK lists the 9mm G17 at 17 rounds and the same-size 40 S&W G22 at 15. With the same maximum pressure behind a heavier bullet, the 40 S&W has noticeably sharper felt recoil for most shooters.
When 40 S&W Still Makes Sense
If you already own a 40 S&W pistol, police trade-in 40s are often good values, and quality defensive loads are widely available. Shoot what you can control and practice with.
Continue your research
FAQ
Is 9mm or 40 S&W better for self-defense?
The FBI’s 2014 testing found modern 9mm duty bullets matched or beat most 40 S&W loads it tested, with more capacity and less recoil. For most shooters, 9mm is the better choice; a 40 S&W you shoot well is still effective.
Can you shoot 9mm in a 40 S&W pistol?
No. They are different cartridges. Only use the cartridge stamped on your barrel, unless the maker sells a dedicated 9mm conversion barrel for that model.
Does 40 S&W have more recoil than 9mm?
Yes for most shooters. Both have a 35,000 psi SAAMI maximum, but the 40 S&W pushes a heavier bullet, so felt recoil is sharper in the same-size pistol.