Locating fastener for firearm optic

An apparatus, comprising:

• a locating fastener including a threaded section and non-threaded shoulder;
• a firearm part including a mount, the mount arranged to receive a direct-mount optic sight or an adapter on which another optic sight is mountable, the mount comprising a surface;
• a locating fastener opening in which the locating fastener is installable to attach, to the firearm part, 1) the direct-mount optic sight or 2) the adapter, the locating fastener opening including:
• a threaded hole to mate with the threaded section of the locating fastener;
• and
• a counter opening located above the threaded hole, wherein the counter opening is arranged to slip fit with the non-threaded shoulder of the locating fastener to align a center axis of the locating fastener with a center axis of the locating fastener opening;
• wherein when the direct-mount optic sight or the adapter is attached to the firearm part using the locating fastener, the non-threaded shoulder extends below said surface of the mount.

A kit of parts, comprising:

• an adapter to mount, to a firearm part, an optic sight, the adapter characterized in that it includes:
• an optic footprint corresponding to an underside of the optic sight, and
• a counter opening;
• a locating fastener to mount the adapter on a surface of the firearm part, the locating fastener characterized in that it includes:
• a portion to extend into the adapter, wherein at least some of the portion is locatable in the counter opening, and
• another portion to extend below the surface;
• the locating fastener including a threaded section to mate with a threaded hole in the firearm part;
• the locating fastener further including a non-threaded shoulder arranged to slip fit with another counter opening, to align a center axis of the locating fastener with a center axis of the other counter opening;
• wherein when the adapter is mounted on the surface using the locating fastener, the non-threaded shoulder extends below said surface.

A firearm part, a firearm assembly, or a firearm, comprising:

• a mount arranged to attach thereto, using one or more threaded parts, a direct-mount optic sight or an adapter on which another optic sight is mountable;
• a surface of the mount including:
• one or more openings to receive the one or more threaded parts, respectively, and
• a footprint associated with:
• a portion of an underside of the direct-mount optic sight, or
• a portion of an underside of the adapter, and
• at least one opening of the one or more openings coincident with the footprint;
• the at least one opening arranged to align a center axis of a respective one of the one or more threaded parts with a center axis of the at least one opening during installation of the respective one of the one or more threaded parts in the at least one opening, each opening of the at least one opening including:
• a threaded hole to mate with a threaded section of the respective one of the one or more threaded parts;
• and
• a counter opening located above the threaded hole, wherein the counter opening is arranged to slip fit with a non-threaded shoulder of the respective one of the one or more threaded parts to align the center axes;
• wherein when the direct-mount optic sight or the adapter is attached to the firearm, the firearm assembly, or the firearm part using the one or more threaded parts, the non-threaded shoulder(s) extend below said surface of the mount.