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EXD Engineering Vertical Reticle Instrument - brilliantly simple!

17855 Views 61 Replies 21 Participants Last post by  construe24
A few weeks back, I read a post by Smoothtrigger about the EXD Engineering Vertical Reticle Instrument, and I immediately knew that I had to have one.

The device arrived this past week, and yesterday I double-checked the scope installation on 8 different rifles. As good a job as I thought I had done previously, 4 of the 8 benefited from some minor fine tuning.

I don't know whether to characterize the instrument as simply brilliant or brilliantly simple!

There is no requirement for what one might perceive to be a flat surface on either the scope or the rifle, because the device helps ensure that the optical centerline is in the same vertical plane as the bore by indexing at two points each on the objective bell and the barrel (or less optimally the top of a picatinney rail on an AR that I double-checked).

One simply supports the rifle / optic combination in the vertical as indicated by the single bubble level, and then rotates the scope within the rings to align the reticle with a suspended plumb bob. I chose to do this indoors so as to minimize any environmental influences.

Hopefully most folks appreciate the critical importance of not having the reticle canted with respect to the optical centerline / bore plane when it comes to shooting at variable distances, whether the technique employed be dialing-in or holding over.

Here is the setup that I used in my foyer to support the rifle:

And a slightly closer pic of the instrument on the scope and rifle:

And finally, the plumb bob in my den about 11 yards away from the rifle. I found that using the bright red string contrasting against the black reticle and background worked excellently:

I quickly learned that by slowly sliding the rear of the rifle vise slightly back and forth sideways (while keeping an eye on the bubble level), it was easy to get extremely precise alignment with the string by watching it appear and disappear behind the reticle along it's length. It is a little hard to describe the technique, but hopefully it makes some sense.

While I have been able to do a good job mounting optics over the past three and a half decades without this tool, using the tool makes it very much quicker and easier, and with an associated higher level of confidence in the results.

Of course, while the true test of any optic setup only comes at the range, it is my expectation that any remaining error will be very slight, if at all.

It would be hard not to recommend this tool to anyone who has the desire to easily and reliably mount a scope on virtually any rifle with a high degree of precision.

Thank you Kevin for originally posting about this fantastic tool.
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· Registered
7 Posts
Keep it simple! A crosshair that is not plum to the bore/action will have an effect on shot placement and the more wind deflection and the further the distance the bigger the effect.

we set up on a plum line and a long horizontal level at 100 yards. Get the rifle set up level with an action level, move scope to get crosshairs level to the plum line/horizontal level and tighten scope rings. I use a top scope ring level so it gets trued up to the action as the rings are tightened.

Nothing worse than looking at a target with a leveled rifle and crosshairs are canted. It really shows up at a long range centerfire target.

· Registered
735 Posts
No, thank you for an excellent review and explanation of how this tool works.

As we discussed, without a hands on demo of this tool, I haven't been able to light a fire under this. It makes mounting scopes so easy, and with such precision that it's a must have IMO.

Every one of my ranges members that I've shown this to, often when working on their scopes, has purchased one.

But here at RFC it seems most folks either think they've got scope mounting down, or don't quite get what this device does.

I think you may want to modify your threads title to something like.

:Scope mounting for Dummies.
:So you think you know how to mount a scope.:) Sure you do.

You know, a statement that gets people going like ......What, how dare you.

Anyway nice write up.

I have been using this piece of equipment for about 15 years. First came across it when the designer showed it at an airgun match in Baton Rouge, La. Works like a charm and saves a lot of ammo and frustration. I my case the edge of the tv set happens to be plumb in the vertical so that's what I use for alignment.
One other point to consider. The scope reticle may not be optically centered. In a conversation with Leupold one day the tech told me the best way to determine that, if you don't have the technical equipment, is to avail yourself of a mirror. Normally a bathroom mirror will suffice. Turn the bathroom light on and hold the scope flat against the glass. you will see the reticle in the scope and an image projected on the glass. if they coincide you are home free. If not the adjust the turrets till they do. Always adjust the elevation first then the windage.
For folks who use a bore sight tool when setting up a scope on a 22Lr rifle know that if you set the scope up so that the crosshairs are slightly below the point of aim will pretty much put you target at 50 yds. If you have never done that try to bore sight your rifle that's zeroed at 50 and see if that's not true.
Hope this helps. Oh one other point don't try to install a bubble level on a scope unless you have done the above.
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