It is just an HBAR. IIRC it is thicker than a standard HBAR and the receiver was reinforced. Also was designed to fire from an open bolt. Has no barrel change capability. Neat looking but it doesnt provide much if any improvement over an HBAR unless you have a registered lower. I would think that a fluted heavy or super heavy barrel with a good free float handguard for ventilation would provide better accuracy and be much cheaper.