Level

There's nothing more fun than doubting if a scope is mounted level because the crosshairs are canted when resting on a bipod.

Either the bipod has one leg longer than the other, its base is canted or the swivel stud it's mounted to is off center.

Because I've checked that the scope is level with the gun now.

This just doesn't come up with scopes with built in bases like you often see on AR's.