A .40 S&W Glock 23 pistol can be adapted to fire 9mm ammunition through the use of a replacement barrel. This simple change maintains the original frame and slide but alters the chambering to accommodate the smaller cartridge. Typically, these barrels are drop-in installations, requiring no gunsmithing. A magazine designed for 9mm Glock pistols is also required for proper feeding.
Adapting a Glock 23 to 9mm offers several advantages. The most significant benefit is reduced ammunition cost, as 9mm rounds are generally less expensive than .40 S&W. Furthermore, the reduced recoil of 9mm can improve shooter control and accuracy, particularly for those sensitive to recoil or newer shooters. This conversion allows for increased training frequency due to the lower cost per round, ultimately enhancing proficiency. Historically, caliber conversions have been a popular way to increase the versatility of firearms platforms.