We customize Glock slides with vented windows and ported barrels. We customize slides and port barrels for the Glock 19, 19X, 17, 26, 43X, and 45. So why port the barrel on your favorite Glock? On the other hand, a ported barrel contains holes close to the muzzle. As a result of the holes' upward orientation, propellant gases are vented there after the bullet has left the barrel. As a result, when the handgun fires, some force is applied downward. This push helps the shooter keep their focus on the target by compensating for muzzle flip.