9mm vs 40 S&W: Is the Downgrade Worth It?

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9mm vs 40 S&W: Is the Downgrade Worth It?

Why Law Enforcement Originally Chose .40 S&W

The .40 S&W was developed in response to concerns following a 1986 FBI shootout where 9mm rounds were seen as underperforming. It offered a larger bullet diameter and more energy than the 9mm while avoiding some of the capacity and recoil drawbacks of the .45 ACP — a genuine compromise cartridge that made sense for its era.

Why Agencies Are Switching Back to 9mm

Modern 9mm defensive ammunition, like the 9mm 124-grain JHP Federal HST option, has closed the performance gap that originally justified the .40 S&W's existence. Extensive testing has shown that well-designed modern 9mm hollow points achieve very similar terminal performance to .40 S&W, while offering meaningfully less recoil, higher magazine capacity, and lower cost per round.

The FBI itself, whose testing originally helped drive the shift toward .40 S&W, later reversed course and returned to 9mm as its standard sidearm cartridge, citing exactly these factors — a fairly definitive real-world verdict from the agency that started the trend in the first place.

Recoil Differences

The .40 S&W generates noticeably sharper recoil than the 9mm, largely due to its higher operating pressure combined with a similar-sized (often identical) pistol frame. Many shooters find this recoil more difficult to manage for fast, accurate follow-up shots, and it also tends to accelerate wear on pistols not specifically over-built for the cartridge.

Cost and Capacity

The 9mm remains cheaper to shoot, both for practice ammo like the 9mm 115-grain FMJ Magtech load and for defensive ammunition, and it typically allows for a couple more rounds of capacity in an identical pistol frame compared to .40 S&W, since the cartridge itself is slightly smaller in diameter.

Is There Still a Case for .40 S&W?

If you already own a .40 S&W pistol that you shoot well and trust, there's no urgent need to switch — it remains a fully capable defensive cartridge with a long track record. But if you're starting from scratch, the practical advantages of 9mm (cost, capacity, recoil, and ammo availability) make it the more sensible default choice for the vast majority of shooters today.

The Bottom Line

The .40 S&W isn't a bad cartridge — it's just been surpassed in practicality by advances in 9mm ammunition design. Unless you have a specific reason to prefer it, the 9mm offers a better overall package for most defensive shooters. You can find 9mm ammunition for both carry and practice at the BulkAmmoToGo shop.