Abstract: An accessory which becomes an integral part of a semi-automatic firearm whereby a detachable box magazine is converted to no longer be immediately separable for exchange with another magazine. The firearm is preferably an AR-15 firearm which is modified by the accessory to pivotally mount the firearm's magazine to a non-removable shroud affixed to the firearm. The magazine shroud includes a retaining band which generally encircles the magazine, and provides a track to allow the magazine to be disengaged from the firearm and dropped sufficiently therefrom to be tilted to an open position for loading and unloading cartridges.