I'd guess that of all the scoped rifles I've handled, probably ninety percent have the crosshairs out of vertical alignment. The reason is that when you look through the scope you have your head canted, and when the vertical crosshair looks straight to your crooked head, it ain't. Crooked scopes cause you to cant the rifle, which causes the bullet to fly to the right or the left of the axis of the bore, which means you're going to miss right or left when you shoot at 250 yards or more.
Over the years I've seen various gadgets that purport to enable you to mount the damned scope straight. A couple of days ago, however, I learned about a way to do the job that is sublime in its simplicity and requires only a carpenter's spirit level. Here's how it works:
1. Go to the rifle range. Set your unloaded, open-bolted rifle on the sandbags and brace it solidly. Find a flat spot on the receiver and lay the spirit level across it to see if the rifle is vertical. If it isn't adjust accordingly.
2. Hike down to 25 yards and set up a target. Using the spirit level, draw a vertical line in an attractive spot on the paper and then apply a piece of black tape that aligns with the vertical line.
3. Go back to your rifle and, with excruciating care, set your scope in the rings and align it so your vertical crosshair is parallel with the tape on the target. Now it's time to tighten your ring screws.
4. If you have rings that torque the scope tube clockwise or counterclockwise (a lot of them do) you're probably due for a half-hour of serious aggravation. The best way to handle the job is by tightening things very gradually and checking alignment as you go. Avoid the temptation to emit little shrieks of rage or throw things.
5. If, when you finish and mount the rifle to check the sight picture the crosshair doesn't appear vertical, don't worry, it is. You are crooked, not your scope.
Photo by AMagill on Flickr