Redefining perceptions of semi-automatic 5.56 performance"" the Hellion from Springfield Armory represents a radically unique and innovative approach to firearms design. Featuring both compact dimensions and capable downrange performance"" the Hellion with 20"" barrels offer bullpup fans even more options. With the action located behind the trigger"" the 5.56mm Hellion offers extremely compact dimensions even with these longer-barreled new variants. In addition to enhanced ballistic performance with both models"" the 20"" version comes standard with a ribbed barrel for maximum rigidity and heat dissipation. It also is capable of accepting a military-pattern bayonet on its integrated bayonet lug. Fully ambidextrous controls and reversible ejection round out the package for maximum adaptability.