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Rifle Scopes USO SN3 Reticle/EREK Knob config.

BenTerrible

BenTerrible

Which way did my bullet go?
Full Member
Minuteman
May 26, 2009
206
17
40
#1
USO SN3 5-25 x 58
34mm tube

My scope has the RDP-MOA reticle, and the 1/10 mil 110 click milestone elevation knob.

I am looking for some clarification on why I would want an MOA reticle paired with a MIL elevation knob. I am new to precision shooting and I am hoping to have someone aid with an explanation on how my system (reticle/elevation knob configuration) is designed to work.

Again, new to the long range side of shooting. Just looking for some help with the equipment I currently have.

How to zero the knobs once the scope has been zeroed.

Maybe a breakdown of how the 1/10 MIL EREK knob works.

I apologize in advance if this is another question that has been answered repeatedly.

Thanks in advance for any help!

-BT
 
#2
Re: USO SN3 Reticle/EREK Knob config.

You are saying you already own the scope in this configuration? It's pretty rare and doesnt make much sense to have a reticle and knobs that dont match. Especially a USO with all their options.

Pretty much, your holdovers will be in MOA and your Dialing will be in Mils.
 
#3
Re: USO SN3 Reticle/EREK Knob config.

Yes, I own this scope already. Purchased from private party. I don't understand why this type of set up would be beneficial.
 
#4
Re: USO SN3 Reticle/EREK Knob config.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BenTerrible</div><div class="ubbcode-body">Yes, I own this scope already. Purchased from private party. I don't understand why this type of set up would be beneficial.

</div></div>It isn't beneficial.
 
#5
Re: USO SN3 Reticle/EREK Knob config.



Maybe someone can confirm? Here is a photo of the EREK knob.

002_zps67c325d9.jpg
 
#6
Re: USO SN3 Reticle/EREK Knob config.

Did you know it was set up this way before you bought it? I would try and get my money back. If you can't do that, send it back to USO and have them put a Mil based reticle in it. This setup in its current form will do nothing but make your life difficult when behind the rifle.

-SBS
 
#8
Re: USO SN3 Reticle/EREK Knob config.

Consult with USO about this, you will want the click increments and the reticle to be in the same units (mils, MOA, or IPHY). From past experience with USO scopes, it may be easier and less expensive to change the turret mechanism instead of the reticle.

PS Ask USO to confirm that the turret clicks are mils. It's easy to simply swap EREK knobs and maybe that was mistakenly done and the clicks are really 1/4 MOA or IPHY. You can determine this yourself by comparing dialed angular changes with reticle movements.

I've never seen a scope with mil turrets and MOA reticle!
 
#9
Re: USO SN3 Reticle/EREK Knob config.

I am thinking of sticking with MOA over MIL.Thoughts on this? I understand its all personal preference, however, I do understand that MOA is a smaller increment. More precise?

Thank you for all the responses!

-BT
 
#10
Re: USO SN3 Reticle/EREK Knob config.

I prefer mills. But I would listen to Jack. He knows a lot more about USO stuff than I do, I don't run USO. If the turrets are less expensive to change than the reticle, that's the route I would go. But you definitely need to have turrets and reticle with matching units.

-SBS
 
#11
Re: USO SN3 Reticle/EREK Knob config.

I think USO uses IPHY (inches per hundred yards) rather than MOA, but ask them. IPHY is better than MOA because the math is simpler when ranging in yards if you know or estimate target size in inches. Frankly, I prefer IPHY to mils because I'm always thinking of target size in inches (animals, bull's eye diameter,...).
 
#12
Re: USO SN3 Reticle/EREK Knob config.

USO should be able to look up the serial # I think and give you some info on it. Dont know if they are doing reticle or knob swaps though.
Might be better off selling it and putting that money towards a new USO built the way you want it.
 
#14
Re: USO SN3 Reticle/EREK Knob config.

You definitely should have reticle and turrets with matching units.
Whether MOA or MIL is up to you and I would take the units of measure, you are using, into consideration, e.g. if you are using imperial units, MOA probably makes more sense, OTOH if you are using the metric system, MILs are way to go.

It is a strange combination, though.
 
#15
Re: USO SN3 Reticle/EREK Knob config.

It should be an easy fix with swapping out turrets.

I got a scope from them and it was not tracking true, somehow it had the wrong internal turret mechanism or cap, and so they swapped to out at no cost. Now it tracks true and matches what is marked on the turrets.
 
#16
Re: USO SN3 Reticle/EREK Knob config.

Bill,

Thank you for the response! I dug this up and have been reading all morning:

http://www.mil-dot.com/Content%20Images/The_Derivation_of_the_Range_Estimation_Equations.pdf

I am now swaying more towards the MIL system now.

This is an incredible scope! I finally found a spot to shoot and now I am in this mess of rearranging the unit system for both the reticle and knobs. Oh well, not that big of a deal. I will be patient and let USO do the work. I have dealt with them in the past and their customer service is second to none. They are great people.
 
#17
Re: USO SN3 Reticle/EREK Knob config.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BenTerrible</div><div class="ubbcode-body">Planning on calling Monday to inquire about swapping the MIL knob out for MOA.

</div></div>
Since I've never seen a scope with mils on the turrets with an MOA reticle, I suggested you check to be certain that is the case. You can either do it yourself or ask USO who can check using the serial number.

If your scope has mils on the turrets, it's not just a knob change. Both turret's internal mechanisms (elevation and windage) have to be changed mechanically.
 
#18
Re: USO SN3 Reticle/EREK Knob config.

USO has offered both IPHY and MOA as well as MIL. A knob switch will be easy, a reticle switch on the other hand you may as well buy a new one.
 
#20
Re: USO SN3 Reticle/EREK Knob config.

By the looks of it you do have a 1/10 MIL knob. However we do offer a RDP MIL reticle so check to make sure what RDP version you have. You can do this by looking through the scope and look at the horizontal line. If it's an RDP Mil the highest number will be 15. If it's RDP MOA the highest number will be 30. The RDP MOA is a true MOA reticle.

Jason
 
#21
Re: USO SN3 Reticle/EREK Knob config.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ssgtkyle</div><div class="ubbcode-body">By the looks of it you do have a 1/10 MIL knob. However we do offer a RDP MIL reticle so check to make sure what RDP version you have. You can do this by looking through the scope and look at the horizontal line. If it's an RDP Mil the highest number will be 15. If it's RDP MOA the highest number will be 30. The RDP MOA is a true MOA reticle.

Jason </div></div>


Jason-

Just double checked the reticule and I confirmed that 30 is there on the horizontal. It seems you are a Rep for USO, what's next?

Thanks!
 
#22
Re: USO SN3 Reticle/EREK Knob config.

First, confirm that the turret clicks are really mils, not MOA. While likely that it's mils, someone could have swapped knobs. Swapping knobs doesn't change the internal gearing, only the writing on the knob.

You can compare the change on the dial to the change on the reticle by looking at an object some distance away. If the turrets are really mils, then 5 mils up or down on the elevation turret will correspond to 18MOA up or down on the reticle. USO can look up the serial number and get the build info if you don't want to check it yourself.

If you have a mils/MOA setup, then you need to call USO and get a price on a conversion.
 
#24
Re: USO SN3 Reticle/EREK Knob config.

That is one oddball scope! Wonder why it was ordered like that??? I would recommend selling it and buying a new one from me
grin.gif
 
#25
Re: USO SN3 Reticle/EREK Knob config.


The fix is easy. Have USO to make for you a custom elevation knob in range increments, and then, the difference won't matter. I run mine like this and like it. The only difference between mine and yours is my reticle is subtended in mil.

Learn MOA as opposed to MILS and use your knob for elevation compensation when possible. Shoot the shit out of it for now and get a Bushnell for barely over 1k.
 
#26
Re: USO SN3 Reticle/EREK Knob config.

Still waiting on the details for the scope from USO. I provided them with the serial number and I hope to hear back tomorrow.

Looks like I might have gotten hosed on this deal. Can't imagine this scope would be easy to sell though??? What is it worth???

Thanks again for all the help!

-BT
 
#27
Re: USO SN3 Reticle/EREK Knob config.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Casey Simpson</div><div class="ubbcode-body">
The fix is easy. Have USO to make for you a custom elevation knob in range increments, and then, the difference won't matter. I run mine like this and like it. The only difference between mine and yours is my reticle is subtended in mil.

Learn MOA as opposed to MILS and use your knob for elevation compensation when possible. Shoot the shit out of it for now and get a Bushnell for barely over 1k. </div></div>

Thanks for the suggestion! Added this to the list of questions for US Optics. Maybe this will solve all my problems.
 
#28
Re: USO SN3 Reticle/EREK Knob config.

You can still use the scope, it's not "broken." Dial in your firing solutions in mils with the turrets, and estimate corrections and holdovers using the reticle and a little math.

The RDP-MOA reticle has 2MOA tic marks on the elevation axis, which is about 0.59 mils. So each 0.1 mil click on the elevation turret is about 1/6 of the distance between tic marks on the reticle.

While not really optimum, your scope is still useable for corrections using the reticle with some simple math.
 
#29
Re: USO SN3 Reticle/EREK Knob config.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Casey Simpson</div><div class="ubbcode-body">
Have USO to make for you a custom elevation knob</div></div>
This is a simple, inexpensive, and brilliant solution.

However, I wonder about the windage knob.
 
#30
Re: USO SN3 Reticle/EREK Knob config.


The windage knob? Leave it alone when shooting. Set it for zero, ensure your scope is mounted correctly such that holdovers amount to no windage corrections, i.e; scope elevation must track up and down in a straight line.

Hold into the wind for windage corrections without touching the windage knob.
Pretend its bonded and won't move.
 
#31
Update on this:

Jason at USO got me squared away with this problem! Hands down, best customer service I have ever experience, period. Thank you US Optics!

Next,

Went to the range today and zeroed my rifle at 100 yards. After finding zero and re-setting the EREK knob, I noticed I am about 2 MILS up over the "0" on the scope. See photo for clarification. I suspect this may have something to do with the 0 MOA rail on the rifle (Barrett M98B).

Thoughts please?

IMG_2644_zpsc69be957.jpg


To my understanding, this is essentially lost elevation in the EREK knob. In other words, for longer distance shots I could run out of vertical adjustment.

Thanks in advance,

-BT
 
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