how do i know when my cross hairs are perfectly straight up and down, when it is mounted on the gun? is there a way. i cant imagine you just guess. i have an old scope i want to put on my slug barrel and dont know much about scopes...yet.

They make a level you can use, but I just eyeball it. I mount it loose and then shoulder it a few times to see how it looks. If it's off I rotate it. When I like how it sits I torque the screws down.

Or you could just have a shop mount it for you.

Paul

You know I have thought about this before and I dont see the point The only way I see it mattering is if you carry a level and make sure the gun is perfect level when shooting!