Abstract: A device facilitates adjustment of a sight of a firearm by providing a visible mark on a target when the device is placed within a chamber of the firearm. The device may include a laser module energizeable within the chamber to produce the mark at a position along a laser axis, a power supply situated within the chamber to energize the laser module when an electrically conductive flowpath is completed with the laser module, and an electrical circuit including a conductive part of the firearm through which electrical current flows to complete the flowpath. A method of laser module alignment is also demonstrated involving rotation of and limited linear motion of the laser module.