GLOCK 40 Gen4 in MOS Configuration
The GLOCK 40 Gen4 in MOS Configuration is a GLOCK pistol with the Modular Optic System. This gives you the ability to adapt your GLOCK 40 Gen4 pistol to your environment and concealment needs. The GLOCK 17/34 pistols have an available threaded barrel for use with sound suppressors, compensators, or other muzzle devices. The GLOCK 19/23 pistols can be converted from 10mm Auto caliber to 9mm Luger by changing the magazine well insert and dropping in a new mag release button assembly.