A pneumatic nailer for use with a high pressure fluid source, comprising: a housing defining a storage chamber positionable in fluid communication with the high pressure fluid source; a cylinder positioned within said housing; a piston having a piston head and a driver member extending from said piston head, said piston head being movable within said cylinder, said cylinder and said piston head defining (i) a displacement chamber on a first side of said piston head, and (ii) a return chamber on an opposite second side of said piston head; a sleeve movable with respect to said cylinder between a first sleeve position and a second sleeve position, said sleeve and said cylinder defining a sleeve space therebetween, wherein, when said sleeve is positioned in said first sleeve position, (i) said sleeve space is isolated from fluid communication with said return chamber, and (ii) said return chamber is positioned in fluid communication with atmosphere, and wherein, when said sleeve is positioned in said second sleeve position, (i) said sleeve space is positioned in fluid communication with said return chamber, and (ii) said return chamber is isolated from fluid communication with atmosphere; a valve movable between (i) a first valve state in which said displacement chamber is isolated from fluid communication with said storage chamber and is positioned in fluid communication with atmosphere, and (ii) a second valve state in which said displacement chamber is positioned in fluid communication with said storage chamber and is isolated from fluid communication with atmosphere; and an actuator (104,106) positionable between an actuated position and a deactuated position, wherein (i) when said actuator is positioned in said actuated position, said valve is caused to move to said first valve state and said sleeve is caused to move to said first sleeve position, and (ii) when said actuator is positioned in said deactuated position, said valve is caused to move to said second valve state and said sleeve is caused to move to said second sleeve position. a housing defining a storage chamber positionable in fluid communication with the high pressure fluid source; a cylinder positioned within said housing; a piston having a piston head and a driver member extending from said piston head, said piston head being movable within said cylinder, said cylinder and said piston head defining (i) a displacement chamber on a first side of said piston head, and (ii) a return chamber on an opposite second side of said piston head; a sleeve movable with respect to said cylinder between a first sleeve position and a second sleeve position, said sleeve and said cylinder defining a sleeve space therebetween, wherein, when said sleeve is positioned in said first sleeve position, (i) said sleeve space is isolated from fluid communication with said return chamber, and (ii) said return chamber is positioned in fluid communication with atmosphere, and wherein, when said sleeve is positioned in said second sleeve position, (i) said sleeve space is positioned in fluid communication with said return chamber, and (ii) said return chamber is isolated from fluid communication with atmosphere; a valve movable between (i) a first valve state in which said displacement chamber is isolated from fluid communication with said storage chamber and is positioned in fluid communication with atmosphere, and (ii) a second valve state in which said displacement chamber is positioned in fluid communication with said storage chamber and is isolated from fluid communication with atmosphere; and an actuator (104,106) positionable between an actuated position and a deactuated position, wherein (i) when said actuator is positioned in said actuated position, said valve is caused to move to said first valve state and said sleeve is caused to move to said first sleeve position, and (ii) when said actuator is positioned in said deactuated position, said valve is caused to move to said second valve state and said sleeve is caused to move to said second sleeve position.