A rapidly deployable and adjustable arm support apparatus to be fastened to a user's body or user's apparel to support the arm of the user holding a rifle, bow, camera etc. In accordance with an example embodiment of the present invention, the adjustable arm support platform includes an arm support and a first extension member connected to the arm support. The arm support is adjustable along at least a first dimension and is shaped to accommodate a shooters arm. A second extension member is rotatably connected to the first extension member, wherein the first extension member is rotatably adjustable relative to the second extension member. This flexibility of orientation means that the user's arm can be comfortably supported in virtually any reasonable orientation relative to the shooting platform.