The FBI recently determined that the 9mm is the ideal caliber for a defensive pistol and are making the switch, as such, many law enforcement agencies are following suit and changing their duty pistols from .40cal to 9mm. This means there’s lots of surplus .40cal pistols on the market, many of them Glocks.

These police trade in .40cal Glock 23s can be acquired quite cheaply, and usually in quite good condition. But since .40cal ammo is declining in popularity, it’s becoming harder to find and more expensive. Thankfully, there are 9mm caliber conversions for these .40cal Glock 23s.

Simply remove the .40cal barrel from your Glock and add in a 9mm conversion barrel and you’re good to go!

Please note that a standard 9mm barrel won’t work in a .40cal Glock, it needs to be a 9mm conversion barrel.

Glock 9mm & 40cal Conversion Barrels

The standard 9mm barrel has a little bit of wiggle in the .40cal Glock 23. The 9mm conversion barrel for the Glock 23 is specifically designed to be ever so slightly larger and remove that wiggle, ensuring an accurate 9mm Glock 23.

Wheaton Arms 9mm Conversion Barrel

Let’s dive into the caliber debate – 9mm vs .40cal vs .45acp. Which do you prefer? More capacity and less recoil? Or a larger bullet with less capacity?