The extinction of the .40 S&W is anything but imminent. It remains a popular cartridge, and it’s proven itself in many police shootings. Many law enforcement agencies continue to use it. But the fact remains: Many are moving away from it—mostly to the 9mm—for several good reasons.

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Early on, the 9mm suffered from a lack of efficiency, mostly due to its construction, which resulted in either under- or overpenetration. At the time, the newly developed .40 S&W answered the call. Developed from scratch as a duty round, it seemed to offer some advantages. Mimicking the 10mm FBI load in a smaller pistol, it simply worked, and its terminal ballistics were on par with the .45 ACP without the 10mm recoil. It seemed like a perfect solution.

But the 9mm has been improved. Across the board, it is much more effective, virtually flat-lining penetration, expansion, accuracy and effectiveness among common pistol calibers. Data from actual shootings proves this, showing no measurable difference in effectiveness amongst the three main 9mm, .40 S&W and .45 ACP chamberings. Shot placement—not one magic bullet or a minor difference in caliber—is the most critical element. And no pistol round facilitates better shot placement than the 9mm.

Reliability & Recoil

Most early .40 S&W pistols were 9mms converted to take the new chambering. This changed with time of course, but .40 S&W versions can still be problematic by comparison. So I had to wonder: Why deal with reliability issues when the 9mm always works?

While recoil control is not a pistol issue, per se, it remains critical and causes problems for some law enforcement officers. When it came to training, if an officer was having trouble with a .40 S&W, my simple solution would be to hand them the same gun in 9mm. Almost without fail the problems disappeared. And ultimately what you want is for your officer to feel confident with their firearm and hit what they are aiming at. If changing to a 9mm pistol does that, then all the better.

Capacity & Cost

While I understand that officers did it with “five shots and a revolver” in the old days, there is a reason those days are over. If you can carry a pistol that is roughly the same size with a higher capacity, then you are foolish not to, especially in a duty situation. Eight rounds is fine—unless of course you needed 10 on that day, or 17! With everything else being equal, the more capacity the better.

Ammunition is costly, and prices probably won’t come down anytime soon. For a police agency, the difference between purchasing 9mm and .40 S&W ammunition can add up to tens of thousands of dollars. Maintaining the same level of training for less money is just a budgetary reality. With no proven loss in effectiveness, possible gains in proficiency and thousands of dollars in savings, it is a no brainer.

Making The Switch

Yes, the .40 S&W works—there is just nothing to prove it works any better than the 9mm. As long as that remains true, LE agencies are going to keep migrating back to the 9mm, and in my opinion they should. I carried a 10mm pistol for years, but the pistol on my hip is more often than not a 9mm these days, and that is not likely to change any time soon.