The 4XNikon ProStaff scope that had been onmy old Stag Horn for about five years would no longer hold zero. Put it in the junk scope box. Last week I bought a Savage model 93.22 Magnum. Had no scope for it. Took that Nikon scope,centered the reticle and put it on the .22.Zeroed the gun and it shoots great. Nothing wrong with the scope.

Not sure why the scope went haywire and is now OK. Those Pro Staff scopes are great.