Every year the wise and ethical hunters head to the range to confirm that their scoped rifles or slug guns are properly sighted-in. Mysteriously, some of the scoped guns are no longer sighted-in. This sends legions of hunters scratching their heads as to how this could be. After all, they reason, it was sighted-in when they shot it last season.
To the outside world riflescopes appear as a metal tube with a glass lens at each end. Unseen are several lenses and a second metal tube hidden within the first. This hidden, inner tube is the erector tube and it lies in the rear half of the scope. The forward end of the erector tube is held by the scope's elevation and windage adjustments and an elastic part.
When the rifle, or slug gun, is fired the erector tube is microscopically tossed to and fro. When the scope stops vibrating, the erector tube may have been displaced a small amount. Heavier, brass erector tubes are more likely to suffer this malady than light, aluminum tubes. Allowing the scope to suffer bumps and impacts prior to use can do the same thing. Unfortunately in scopes, even microscopic movement can have big consequences. We know this microscopic movement as "reticle shift".
And as Paul Harvey would say, "Now you know...the rest of the story."
To the outside world riflescopes appear as a metal tube with a glass lens at each end. Unseen are several lenses and a second metal tube hidden within the first. This hidden, inner tube is the erector tube and it lies in the rear half of the scope. The forward end of the erector tube is held by the scope's elevation and windage adjustments and an elastic part.
When the rifle, or slug gun, is fired the erector tube is microscopically tossed to and fro. When the scope stops vibrating, the erector tube may have been displaced a small amount. Heavier, brass erector tubes are more likely to suffer this malady than light, aluminum tubes. Allowing the scope to suffer bumps and impacts prior to use can do the same thing. Unfortunately in scopes, even microscopic movement can have big consequences. We know this microscopic movement as "reticle shift".
And as Paul Harvey would say, "Now you know...the rest of the story."