40 S&W vs 10mm
40 S&W vs 10mm – Differences, Power and Which to Buy
Comparing 40 S&W vs 10mm is a story of one cartridge and its shorter offspring. In simple terms, both fire the same .40" bullet, but the 10mm Auto has a longer case and a higher pressure limit, so it can drive the same bullet harder.
Quick Verdict
- 10mm Auto: longer case, 37,500 psi SAAMI max, the woods and hunting choice
- 40 S&W: shorter case, 35,000 psi, fits 9mm-size frames
- Both: 15 rounds in full-size GLOCKs (G20, G22)
Winner for most users: 10mm for backcountry and hunting; 40 S&W for compact carry and lower cost.
Side-by-Side Specs
| Spec | 40 S&W | 10mm Auto |
|---|---|---|
| SAAMI MAP (transducer) | 35,000 psi | 37,500 psi |
| Case length (SAAMI chamber min.) | .850 in | .992 in |
| SAAMI standard issued | Feb 1, 1990 | Jul 18, 1989 |
| GLOCK full-size capacity | 15 (G22) | 15 (G20) |
| Best For | Carry, duty trade-ins | Woods carry, hunting |
Where 40 S&W Came From
The 40 S&W is essentially a shortened 10mm. SAAMI issued the 10mm Auto standard in July 1989 and the 40 S&W in February 1990. The shorter case let the round fit pistol frames sized for 9mm.
Power and Uses
With a longer case and a 37,500 psi limit versus 35,000 psi, 10mm loads can push heavier bullets faster. That is why 10mm is popular for woods carry and hunting, with hardcast and heavy-for-caliber loads, while 40 S&W stays common in duty and carry pistols.
Can a 10mm Fire 40 S&W?
Do not do it unless the pistol maker approves it. The 40 S&W headspaces on its case mouth, and in a 10mm chamber the shorter case can sit too deep. Some shooters use a dedicated 40 S&W conversion barrel instead.
Continue your research
FAQ
Is 10mm more powerful than 40 S&W?
Yes. Both fire a .40" bullet, but the 10mm has a longer case (.992 in vs .850 in) and a higher SAAMI maximum pressure (37,500 psi vs 35,000 psi), so it can drive the same bullets faster.
Can you shoot 40 S&W in a 10mm?
Only if your pistol maker approves it. The shorter 40 S&W case headspaces poorly in a 10mm chamber. The safe route is a dedicated 40 S&W conversion barrel.
Which came first, 10mm or 40 S&W?
The 10mm Auto. SAAMI issued its standard in July 1989; the 40 S&W followed in February 1990 as a shorter version.