An improved reference sight mount device for use with a gun. The referenceight mount attaches to a gun tube having a mount receiving zone near the tube muzzle end. The mount includes a bracket for mounting a reference sight, and includes a band having a conformed internal diameter conforming to the receiving zone. The mount has an integral sight mounting bracket thereon and a lock for engagement with the gun tube. Three embodiments are described. In one embodiment, the mount receiving zone includes a shrink fit zone and the mount includes a conformed zone formed by a band having an internal diameter sized to expand upon heating and shrink into conformity with the mount receiving zone. In the preferred embodiment, the mount receiving zone includes a tapered press fit zone near the tube muzzle end and the band includes a tapered internal diameter press fit zone. The third, in addition to the features of the above preferred embodiment includes an integral, tailored, flexible isolation member between the band and optical reference sight housing.