Do you shoot with a bubble level attached to your bases? If not might want to re-think that.
Target boards are nice but not always the most accurate. hanging aplub line insures straightenss as well if not better than anything.
You need to make sure your action is level. Typically if you have a flat scope base you can easily do this.
find aplace in your house or go to a building that has room and hangle a thing piece of white rope with a weight on the end. Heavy enough to insure the rope is very straight.
You need then to put you rifel in a vice or insure your rifle ( action is level )
We would like to think allturrets and cross hairs are square but they often are not. Placing a level on the top turret isn't always accurate.
Because I shoot well beyond 500 yards on a regular basis. I found out light years ago the easiest way to miss is rifle cant. Many over look this. Therefore the bubble levels that mounts to you base have always worked the best.
Brownells has some and USO makes a very nice one.
I would stay away from the scope mounted ones as they are kind of a pain to get "square" to your action and match your crosshairs.
Once you rifle action is level using a plumb line is the easiest way to match your verticle cross hair.
Another neat thing is to go to Home Depot or Lowes and get a lazer line level you cna mount this on any wall the you can press a thumb tac into.
If you turn the lights off in a rommo ro dim them the red laser shows up very good against the black cross hairs. Most of thies laser line levels have a multiple buble levels built right into them.
Hope this helps. Although gyroscopic drift may have some input. I doubt 3moa of it is applicable.
Yes, I recently added a Sinclair Anti-Cant Device or scope mounted buble level because I figured I must be canting the rifle. Prior to that I had a verticle line on my target (4'X4' piece of plywood) and would plumb the line when setting up the target. While shooting at 1000 yards I would try to allign my crosshair with the plumb verticle line on the target.
It seems many who replied have found that the elevation turret and and horizontal cross hair is not always parralell (mine isn't). Does this condition necessarily create a problem when dialing up the scope? If so I better send it in to Leupold as several here have suggested.
i would call leupold and ask them, they are very helpfull and will answer any questions you have. leupold (503) 526-1400 also if you do much shooting off a harris bipod i would get a pod-lock. Michael
I'm dealing with this very same dilemma right now on a 8.5-25 Mk4. I always had to dial in wind out farther. I carefully re-adjusted the scope in the rings with feeler gauges between the rail and the underside of the scope body. I also installed a USO level. Now have to dial no wind but yes the reticle is canted :( Off to the repair depot. Unfortunately for us Canucks they don't repair the Mk4's up here.
Another note on the USO level (swing out one) when they mill out the pivot slot, the corners are still proud and the level was off when checked against two other levels set on top of the picatinny rail. A bit of carefull work with a needle file took care of that. Just something to watch for.