I recently got an ACD and through the process of mounting it it appears that my reticle is canted .2 degrees to the left in relation to the elevation turret cap. I found this by using 2 digital levels along the rifle receiver and the turret cap in conjunction with a plum bob at 50 yards.
So my question is:
How common is this degree of cant in lower end tactical scopes?
How much will it effect my shooting?
Vortex said they would replace my scope, but Im worried I will just get sent back another one with the same or worse cant if this is just what their tolerances are.
I'm impressed that you took the time to measure the alignment error. You must be as OCD as I am.
I'm confident that the manufacturing variation at the factory is larger than 0.2 deg. I regularly see errors larger than that magnitude in production scopes. You probably have a good sample. I would not exchange it.
The worse-case aiming error is only 1-2" at 1,000 yds, which isn't much by most standards. You can mitigate that error somewhat, depending on how you align the ACD to the scope. I recommend that you plumb the elevation turret axis if you're dialing elevation, or plumb the reticle if you're holding off elevation. There may still be a small aiming error, however, when dialing a large elevation and hold off a high crosswind correction. Even still, error in wind estimation will probably dominate the reticle cant error.
FYI, most spirit levels used in ACDs have a sensitivity of 0.25 deg per millimeter of bubble movement. In the field most people will have difficulty holding the rifle cant during a shot to better than +/-0.25 deg (+/- 1 mm of bubble movement). The alignment error in the scope reticle is already lower than typical cant errors when an ACD is used.
Thank you for this reply. It actually makes me feel better about the issue. Maybe I wont return it. Vortex told me this morning that its a grey area for them so they would need to check it out and cant guarantee me anything over the phone.
If I remember right the spec that some other optics manufactures use is 3% out, don't know about vortex, heck just putting a level on the cap does not really tell you anything other than the reticle and cap have a .2 cant, I would check the reticle to turret movement.
"Pain is weakness leaving your body"
I have a 6-24x50 PST in FFP that I just received Thursday and it has a little bit of cant as well. I checked it against a door jab at my house which I too used a digital level and verified that the door jab is vertical (89.9 degree's which is actually pretty good if you have ever tried to measure wall/jabs at your house, you would be amazed at how many are not vertical). Anyway, my reticle is also canted a little bit to the left. Unlike you I have not measured the exact amount as my level is simply too large to reliably put on top of the cap to measure the exact difference, but it is off by a small amount. Very small to be sure, but it is none the less off.
I first noticed it when I put the Vortex bubble level on and aligned it to the turret. When I put the reticle on the door jab the bubble was buried hard left. So I thought maybe the bubble was not level in its mount so I aligned the windage turret up with the door jab and the bubble was perfectly level, but the reticle was canted to the left of vertical as related to the door jab.
I do not know if I am going to send it back or what I am going to do. I have tried to convince myself that it is just me seeing something that is not there, but the more I measure and re-measure the more obvious it is that it is not me. I do know that none of my other scopes have this issue from various other manufactures.
It could be machining tolerances on the turret cap itself. I always use a plumb bob at about 40-50 yards to level up my reticle and then check the run out by turning the elevation turret up and down on the plumb bob to see how the true the tracking is. My PST has the tiniest amount of run out from the bottom all the way to the top of the adjustment range, about half the reticle width on one side at the bottom to half a reticle width on the other side at the top of the adjustment range. My Razor HD is absolutely perfect, and has been checked several times for this by me and other much better shooters and techs than myself. Any internal error in my PST can not be seen by me at distance because I am just not that good of a shot, and as another poster said even the smallest amount of error in your hold or movement when the shot breaks will have a greater effect on the point of impact.