A positively aligning, quick mount assembly for interfacing an auxiliary sighting device such as an optical scope with a firearm is disclosed. The positive-aligning quick mount device includes a sight receiver that is attached to a firearm utilizing a firearm interface and includes a mounting ring that supports the sighting device and is configured to be received and retained by the sight receiver. It is further designed to allow quick and easy mounting, removal and re-mounting of auxiliary sights on any firearm while eliminating the need to re-adjust or zero the scope when it is replaced in its mounted position on the firearm.