A rifle scope bubble level on your scope is a must have for shooting beyond 400 or 500 yards.
Bubble levels are available on Amazon and elsewhere online. You must determine your scope diameter before ordering.
1″ Scope diameter rifle scope bubble level:
30mm Scope diameter rifle scope bubble level:
34mm Scope diameter scope bubble level:
Another option for a rifle with a Picatinny rail is to get one of these:
I have experienced the level portion coming loose, so a drop of super-glue to hold the glass to the black frame is smart.
When you are ready to install, remember that the bubble (which is the same as “the world”) must be level with the cross-hairs. You can hang a makeshift plum bob and then make sure the vertical line in your scope is lined up with the string and that the bubble is also level. You can also put a target frame out, then carefully staple a target on, making sure the target is 100 level. Using a lead sled or other vise-like device is handy.
Another method is to make sure the top scope cap is level, and then level the new scope bubble level with it. Wheeler sells a kit that makes this easy:
What questions do you have? 🙂