Crossbows: Proper Scope Mounting
If your crossbow did not come with a scope factory-mounted or you wish to purchase a different scope, you will also need to purchase a set of rings that are compatible with both the scope, and the scope base. However, keep in mind that many scopes do come with the rings, but check to be certain.
The rings are what the scope will actually be mounted into, and they secure to the base. It is recommended to always check the base (picatinny rail on top of crossbow) to ensure that the screws are tight before attaching the rings.
Once you're certain the scope base is tight, it's time to set the scope in the rings, level the crosshairs, and set your scope position to accommodate the correct eye relief for your hold position. Lay the scope into the lower ring halves, and then attach the upper rings using the supplied screws. Do not tighten them at this point. You will want to tighten them just enough to be able to rotate the scope as well as slide it toward and away from your eye.
Mounting a scope is best done on a bench.
This process is best performed on a bench if possible. Get the crossbow positioned in such a manner that it is perfectly horizontal. A level is recommended to assist you if you have access to one. If needed, put blocks of wood under the crossbows limbs. The limbs must not be tilted at any angle to the ground. The crosshairs must also be perfectly vertical and horizontal in relationship to the crossbow's rail and limbs.
It is best to set the eye relief first, by sliding the scope in the rings until your sight picture is clear in relationship to your cheek weld on the stock. Once you are comfortable that you have the correct eye relief, you are ready to rotate the scope into alignment with the crossbow.