This configuration of the Hydra is set up as a 9mm that utilizes Colt Style 9mm SMG magazines.  It includes the Hydra® Modular Lower Receiver with a 9mm SMG-9C Magazine Well, 9mm Colt Style Magazine, the Hydra® Quick Change Barrel Upper Receiver (QCB-D), the Hydra® 16-inch 9mm Blowback Barrel, a 9mm Blowback Bolt, and a B5 systems stock and pistol grip.    With this base rifle, you can purchase and utilize the rest of an ever-growing system including our various magazine wells and caliber conversions. To convert this system to another caliber, the most you will need to change is the barrel, bolt and bolt carrier, and magazine well to the desired caliber.  With caliber conversion kits readily available, this weapon system continues to grow and become the most versatile Black Rifle platform the industry has ever seen.