Firearms having a locked breech are disclosed. manufacturing a plurality of outer members comprising at least a first type of outer member and a second type of outer member having differing shape or configurations;b. The system can take care of all or some of that work. Moreover, the weak posts can allow relatively easy separation of the substrate from the gallium nitride semiconductor layer to provide a freestanding gallium nitride layer. The optical code image scanner comprises a lens and an image capture device where the lens is configured to create two distinct focal points using incoming light and the image capture device captures an image using light from the lens. In this case, an allowable upper limit of the number or density of defects produced at the substrate due to the particles in the process for the substrate is determined, and the predetermined relative velocity is set at a value equal to or smaller than the relative velocity obtained when the number or density of defects reaches the upper limit.