A specific spiral pattern machined onto the external surface of a Glock 21 pistol barrel allows for the attachment of muzzle devices such as suppressors or compensators. This spiral is characterized by its unique measurements, including the diameter and the distance between each groove, which must correspond precisely with the internal threading of the attached device for secure and proper function. For example, a common measurement for such a pattern is 0.578-28, signifying a diameter of 0.578 inches and 28 threads per inch.
The ability to attach muzzle devices significantly expands the versatility of the firearm. Suppressors reduce noise and muzzle flash, while compensators mitigate recoil and muzzle rise, improving accuracy and control. This adaptability is particularly valuable for various applications, including sport shooting, home defense, and professional use. The development and standardization of these patterns have played a vital role in the evolution of firearm accessories and their practical applications.
