I have not read the reply's to this question but this is the most accurate way that I have found to make sure everything is straight.
Get a set of parallels and have one set on the bolt raceways. Use this as a flat so that you can level or plum the action. Get the scope where you think it is level. Then around 50 to 100 yards away place a string with a weight on the bottom and hang it off of something. With the action level look and see if the vertical line is on the string. Then once you have that lined up, run the elevation turret and see if it travels off the string. Adjust accordingly.
You will find that a lot of scopes are wayyyy off from the level of the turret. And you will find that some scopes will track left and right when you think the vertical line is straight. It will make you pull your hair out.
I have had a few scopes where I had to either set the scope up for hold over or dialing since the reticle was canted from the turrets. I was told by a few companies that the scopes will pass quality control with a 5 degrees or less alignment between tracking and the reticle.
Wow. Never even heard of that. Didn't consider it being off internally... Thanks for the tip.