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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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I have tried to buy one, but so far no luck.
It occurs to me in looking at this device that considerable accuracy in manufacture and calibration of the bubble would be required to enable it to perform its' intended function.
Any feedback on this issue from those that have them? Is the slide containing the bubble reversible so that the bubble can be checked? Are the Vs machined evenly and in alignment with the central slot and each other? Is the slide a close enough fit to minimize rotation between the two elements?
Interested in your assessment.
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