Abstract: A axis alignment device has been provided which permits a laser beam to be precisely aligned with a gun bore whose axis is being projected, for the purpose of aligning an optical sight. The axis alignment tool's onepiece body inherently improves the accuracy of the design, while being adaptable to mate with a large variety of gun bore sizes. The alignment device includes a universal seating mechanism for mounting in a muzzle. A bore adapter fits over one end of the one-piece body and is adjusted to snugly fit inside the bore. The alignment devices is designed to operate with an array of bore adapters, that fit a corresponding array of bore diameters. The alignment device also includes a rotary switch which acts as a battery housing, so that batteries can be changed without the disassembly of the alignment device.