9mm vs. .40 S&W for Carry
Why agencies went back to 9mm — and whether .40's extra power is worth the snappier recoil today.
The Short Answer
The 9mm-versus-.40 question is largely settled in 9mm's favor for most carriers. The .40 S&W was designed to deliver more energy than 9mm, and it does — but modern 9mm hollow points meet the same FBI penetration and expansion standards, which is exactly why the FBI and many police departments moved back to 9mm. With terminal performance roughly comparable, 9mm's advantages take over.
9mm gives you higher capacity, softer and less snappy recoil for faster accurate follow-ups, cheaper practice ammo, and less wear on the gun. The .40 still hits a little harder and used .40 guns and ammo can be bargains right now, so it's not a bad choice if you shoot it well. But for most people — especially newer or recoil-sensitive shooters — 9mm is the smarter carry caliber.