Quick comparison
| 9mm Luger | .40 S&W | |
|---|---|---|
| Bullet diameter | 9.01mm (0.355") | 10.16mm (0.400") |
| Standard bullet weight | 115–147gr | 165–180gr |
| Typical FMJ velocity | 1,150–1,200 fps (115gr) | 985–1,015 fps (180gr) |
| Muzzle energy | ~340 ft-lbs (115gr) | ~390 ft-lbs (180gr) |
| FMJ cost per round | $0.17–0.25 | $0.24–0.36 |
| JHP cost per round | $0.55–1.00 | $0.55–1.00 |
| Typical magazine capacity | 15–17+ (full-size) | 13–15 (full-size) |
| Recoil impulse | Lower | Notably higher |
| Market trend | Growing | Declining |
The backstory
The .40 S&W was born from a specific event. After the 1986 FBI Miami-Dade shootout — where a 9mm Silvertip failed to reach a suspect's heart after passing through his arm — the FBI concluded their duty ammo lacked adequate penetration. This kicked off a 30-year caliber odyssey. The 10mm Auto was adopted first but proved too much gun for many agents, so Smith & Wesson shortened the 10mm case to create the .40 S&W in 1990: more energy than 9mm, less recoil than 10mm, in a frame size compatible with existing 9mm duty guns.
From the early 1990s through 2014, the .40 S&W was the dominant law enforcement caliber in the United States. Virtually every major police department issued .40 S&W duty pistols (primarily Glock 22 and Glock 23).
In 2014, the FBI reversed course. After extensive testing of modern ammunition, they concluded that advances in 9mm JHP technology had closed the terminal performance gap — and that 9mm's lower recoil and higher capacity resulted in better real-world shooting performance. Most federal and local agencies followed.
Cost per round
9mm FMJ runs $0.17–0.25/rd. .40 S&W FMJ runs $0.24–0.36/rd — roughly 35–45% more.
This gap is widening, not closing. As .40 S&W production volumes decline with falling demand, economies of scale erode. Meanwhile, 9mm benefits from the largest production runs of any centerfire handgun cartridge.
JHP defense ammo pricing is roughly equivalent: $0.55–1.00/rd for both calibers. Federal HST, Speer Gold Dot, and Hornady Critical Duty are available in both.
Compare 9mm prices → | Compare .40 S&W prices →
The surplus market advantage
The law enforcement transition has created an unusual buyer's market for .40 S&W platforms. Used police trade-in Glock 22 and Glock 23 pistols regularly appear at $300–400 — significantly less than comparable 9mm Glocks. S&W M&P 40 trade-ins are similarly discounted.
For budget-conscious shooters, a used .40 S&W duty pistol plus bulk .40 FMJ can be a solid deal despite the per-round premium. The gun savings can offset years of higher ammo costs.
Ballistics
The .40 S&W delivers roughly 15% more muzzle energy than 9mm with standard loads. In practice:
- 9mm 124gr JHP at 1,150 fps: ~364 ft-lbs
- .40 S&W 180gr JHP at 1,000 fps: ~400 ft-lbs
Both calibers meet FBI penetration and expansion standards with modern JHP ammunition. The .40 S&W's energy advantage produces slightly larger expanded diameters in gelatin testing, but the practical difference in terminal performance is marginal with quality ammunition.
Recoil and shootability
The .40's biggest drawback. It produces a distinctly sharper recoil impulse than 9mm — often described as "snappy" compared to 9mm's more manageable push. In the same gun frame (a Glock 22 vs Glock 17, for example), the .40 is noticeably harder to control.
The practical consequences:
- Slower split times — more time between accurate follow-up shots
- More training required to maintain proficiency
- Higher flinch tendency — the sharper recoil encourages bad habits
- Greater fatigue during extended practice sessions
The FBI study specifically cited these factors: officers shot faster and more accurately with 9mm than .40 S&W, and the terminal performance difference didn't justify the accuracy cost.
The .40 is also harder on guns. The snappy recoil impulse accelerates slide wear, and older Gen 3 Glocks in .40 developed a reputation for frame cracking at high round counts. This was another factor that pushed departments toward 9mm.
Magazine capacity
The .40 S&W typically loses 2 rounds compared to 9mm in the same frame:
| Platform | 9mm | .40 S&W |
|---|---|---|
| Glock full-size (17/22) | 17+1 | 15+1 |
| Glock compact (19/23) | 15+1 | 13+1 |
| S&W M&P full | 17+1 | 15+1 |
| S&W M&P compact | 15+1 | 13+1 |
Two rounds may not sound significant, but in a duty or defense context, more rounds provide more margin.
Platform availability
9mm dominates new production with dozens of models across every size. .40 S&W is in structural decline — several manufacturers have dropped .40 S&W models or reduced their lineups. However, millions of .40 S&W pistols are in circulation, and all major ammunition manufacturers continue full product lines.
The .40 S&W is not disappearing. But new gun options are shrinking each year, and the used market is where the best platform deals exist.
When each caliber makes sense
Pick 9mm if:
- You're buying a new handgun and want maximum options
- Training volume and cost per round matter
- You prioritize controllability and fast follow-up shots
- You want the caliber with the strongest long-term market support
The .40 makes sense if:
- You already own a .40 S&W platform and see no reason to switch
- You find a compelling deal on a surplus LE trade-in gun
- You want marginally more energy per round and accept the recoil trade-off
- You reload your own ammunition (component availability is good)
Related comparisons
- 9mm vs .45 ACP — The classic big-bore comparison
- 9mm vs 10mm Auto — Full-power semi-auto comparison
- 9mm vs .380 ACP — The carry caliber size debate
Related caliber pages
- 9mm ammo prices — Current pricing across all retailers
- Cheapest 9mm right now — Lowest observed prices
- 9mm price history — 30-day pricing trends
- .40 S&W ammo prices — Current pricing across all retailers
- Cheapest .40 S&W right now — Lowest observed prices
- .40 S&W price history — 30-day pricing trends
- 10mm Auto ammo prices — The .40 S&W's parent cartridge