A medical device (40, 140, 240, 340, 440) for engaging tissue, the medical device (40, 140, 240, 340, 440) comprising: a housing (42, 142, 242, 342, 442, 542) defining an internal passageway and a longitudinal axis extending between proximal and distal ends of the housing (42, 142, 242, 342, 442, 542), the housing (42, 142, 242, 342, 442, 542) defining a driver guide surface along the internal passageway; a first jaw (44, 144, 244, 344, 444) rotatable relative to the housing (42, 142, 242, 342, 442, 542), the first jaw (44, 144, 244, 344, 444) having proximal (64, 164, 366) and distal (60, 160) ends; a second jaw (46, 146, 246, 346, 444) rotatable relative to the housing (42, 142, 242, 342, 442, 542), the second jaw (46, 146, 246, 346, 444) having proximal (66, 164, 366) and distal (62, 160) ends; an elongated drive wire (22, 122, 422); and a driver (48, 148, 348, 448, 548, 648) having a proximal portion (548p, 648p) engaged with the drive wire and a distal portion (166, 548d, 648d) engaged with the proximal ends (64, 164, 366; 66, 164, 366) of the first (44, 144, 244, 344, 444) and second (46, 146, 246, 346, 444) jaws, wherein the driver (48, 148, 348, 448, 548, 648) is received within the internal passageway of the housing (42, 142, 242, 342, 442, 542), and wherein a longitudinal movement of the driver (48, 148, 348, 448, 548, 648) rotates the first (44, 144, 244, 344, 444) and second (46, 146, 246, 346, 444) jaws relative to the housing (42, 142, 242, 342, 442, 542); wherein the driver (48, 148, 348, 448, 548, 648) includes an intermediate portion (548i, 648i) positioned between the proximal (548p, 648p) and distal (166, 548d, 648d) portions, the intermediate portion (548i, 648i) including a frame and a locking leg (552, 652) connected to the frame, the frame defining an intermediate space, the frame being deformable such that a predetermined longitudinal force differential between the proximal portion (548p, 648p) and distal portion (166, 548d, 648d) of the driver (48, 148, 348, 448, 548, 648) causes the frame to deform and the locking leg (552, 652) to move away from the longitudinal axis into a locking position; characterized in that the locking leg (552, 652), when moved away from the longitudinal axis into the locking position, engages the driver guide surface of the housing (42, 142, 242, 342, 442, 542). a housing (42, 142, 242, 342, 442, 542) defining an internal passageway and a longitudinal axis extending between proximal and distal ends of the housing (42, 142, 242, 342, 442, 542), the housing (42, 142, 242, 342, 442, 542) defining a driver guide surface along the internal passageway; a first jaw (44, 144, 244, 344, 444) rotatable relative to the housing (42, 142, 242, 342, 442, 542), the first jaw (44, 144, 244, 344, 444) having proximal (64, 164, 366) and distal (60, 160) ends; a second jaw (46, 146, 246, 346, 444) rotatable relative to the housing (42, 142, 242, 342, 442, 542), the second jaw (46, 146, 246, 346, 444) having proximal (66, 164, 366) and distal (62, 160) ends; an elongated drive wire (22, 122, 422); and a driver (48, 148, 348, 448, 548, 648) having a proximal portion (548p, 648p) engaged with the drive wire and a distal portion (166, 548d, 648d) engaged with the proximal ends (64, 164, 366; 66, 164, 366) of the first (44, 144, 244, 344, 444) and second (46, 146, 246, 346, 444) jaws, wherein the driver (48, 148, 348, 448, 548, 648) is received within the internal passageway of the housing (42, 142, 242, 342, 442, 542), and wherein a longitudinal movement of the driver (48, 148, 348, 448, 548, 648) rotates the first (44, 144, 244, 344, 444) and second (46, 146, 246, 346, 444) jaws relative to the housing (42, 142, 242, 342, 442, 542); wherein the driver (48, 148, 348, 448, 548, 648) includes an intermediate portion (548i, 648i) positioned between the proximal (548p, 648p) and distal (166, 548d, 648d) portions, the intermediate portion (548i, 648i) including a frame and a locking leg (552, 652) connected to the frame, the frame defining an intermediate space, the frame being deformable such that a predetermined longitudinal force differential between the proximal portion (548p, 648p) and distal portion (166, 548d, 648d) of the driver (48, 148, 348, 448, 548, 648) causes the frame to deform and the locking leg (552, 652) to move away from the longitudinal axis into a locking position; characterized in that the locking leg (552, 652), when moved away from the longitudinal axis into the locking position, engages the driver guide surface of the housing (42, 142, 242, 342, 442, 542).