A mounting apparatus for simultaneous mechanical and electrical attachment to a powered accessory rail, which extends along at least a portion of a length of a barrel of a weapon and which includes a plurality of slots formed along a length thereof and two outwardly-facing surfaces (23R, 23L) along opposite sides thereof, and which also has formed thereon a first electrical contact and a second electrical contact electrically connected to a power source for providing a first and a second electrical connection to the power source, wherein the powered accessory rail includes a switch formed thereon juxtaposed to the first and second electrical contacts (62P, 62N) for applying power from the power source to the first electrical contact when the switch is operated, comprising: a body, comprising: first and second electrical contacts (822, 824-826) formed on the bottom surface of the body to electrically contact the first and second electrical contacts (62P, 62N) of the powered accessory rail when the mounting apparatus is attached to the powered accessory rail, a feature (821, 823) formed on and protruding from the bottom surface of the body for engaging the switch formed on the powered accessory rail and operating the electrical switch when the mounting apparatus is attached to the powered accessory rail, an integral inwardly-facing surface to mate with a first of the outwardly-facing surfaces of the powered accessory rail, and at least one keying feature to align with a corresponding one of the slots in the accessory rail; characterized by: a lever; a latching arm, pivotally connected to the lever via a first pivot pin and having an inwardly-facing surface to mate with a second of the outwardly-facing surfaces of the powered accessory rail; and said lever being pivotally connected to the body via a second pivot pin and operable to force the inwardly-facing surface of the body and the latching arm into mechanical contact with respective outwardly-facing surfaces of the accessory rail, and, when closed, it clamps the mounting apparatus securely around the powered accessory rail, fixing it in all directions. a body, comprising: first and second electrical contacts (822, 824-826) formed on the bottom surface of the body to electrically contact the first and second electrical contacts (62P, 62N) of the powered accessory rail when the mounting apparatus is attached to the powered accessory rail, a feature (821, 823) formed on and protruding from the bottom surface of the body for engaging the switch formed on the powered accessory rail and operating the electrical switch when the mounting apparatus is attached to the powered accessory rail, an integral inwardly-facing surface to mate with a first of the outwardly-facing surfaces of the powered accessory rail, and at least one keying feature to align with a corresponding one of the slots in the accessory rail; first and second electrical contacts (822, 824-826) formed on the bottom surface of the body to electrically contact the first and second electrical contacts (62P, 62N) of the powered accessory rail when the mounting apparatus is attached to the powered accessory rail, a feature (821, 823) formed on and protruding from the bottom surface of the body for engaging the switch formed on the powered accessory rail and operating the electrical switch when the mounting apparatus is attached to the powered accessory rail, an integral inwardly-facing surface to mate with a first of the outwardly-facing surfaces of the powered accessory rail, and at least one keying feature to align with a corresponding one of the slots in the accessory rail; characterized by: a lever; a latching arm, pivotally connected to the lever via a first pivot pin and having an inwardly-facing surface to mate with a second of the outwardly-facing surfaces of the powered accessory rail; and said lever being pivotally connected to the body via a second pivot pin and operable to force the inwardly-facing surface of the body and the latching arm into mechanical contact with respective outwardly-facing surfaces of the accessory rail, and, when closed, it clamps the mounting apparatus securely around the powered accessory rail, fixing it in all directions. a lever; a latching arm, pivotally connected to the lever via a first pivot pin and having an inwardly-facing surface to mate with a second of the outwardly-facing surfaces of the powered accessory rail; and said lever being pivotally connected to the body via a second pivot pin and operable to force the inwardly-facing surface of the body and the latching arm into mechanical contact with respective outwardly-facing surfaces of the accessory rail, and, when closed, it clamps the mounting apparatus securely around the powered accessory rail, fixing it in all directions.