Maxim Defense 508CP 8.75" Barrel .300 BLK 20 Round Urban Grey Hatebrake Tactical Pistol With the same heart and soul of the proven PDX, the 508 features an 8.5" barrel, ideal for when maximum concealment and compactness are important, but not as crucial. Our MDX series firearms are also equipped with the Maxim's HATE BRAKE muzzle booster. This patent-pending device significantly reduces recoil, decreases the flash signature, pushes gasses and concussion waves downrange away from the operator, and improves overall performance.