Golden Eagle Tall Target Test

[Crosshair1]

Just wondering if anyone has carried out a tall target test on a Vortex golden Eagle.

I'm currently in the market for a new scope for my ftr rig, having had a chance to look through the scr1 reticuled version today it would probably be my choice.

The reason for asking is that i've previously carried out a tall test on a buddys ecr1 type and found that turret moa were approximately 9% larger than actual.

Its not a big deal shooting fixed distances but still its something I dont think i could live with.

 

[Bart B.]

As there are tolerances in scope's several lens elements focal lengths, there will be small changes in image size for a given magnification in the plane the mechanical adjustments are referenced to. A few percent spread is normal across all of a given make and model.

This fact is the compromise we all made when internally adjusted scopes replaced the old Lyman, Unertl, Di Simone, Fecker and Litchert externally adjusted ones. With the standard 7.200 inch mount spacing, the tube angle changed exactly 1 inch per hundred yards over 4 clicks moving .002 inch; regardless of magnification.

9 percent seems a bit high. What range did you tall target test at?

Vortex specs state 1/8th MOA click adjustments, but which MOA one do they use; 1.0000 or 1.0472 inch per hundred yards? There's a 4.72% difference across them.

Update........ from their manual "MOA unit of arc measurements are based on degrees and minutes. A minute of angle will subtend 1.05 inch per hundred yards"

 

[Crosshair1]

This was tested at a tape measured 100yds.

The issue initially came to light as the gun it was fitted on was shooting at least 2moa flatter than expected from 100yd zero to 1000yds.

I keep my own tall tests and going back through them i dont have any scope deviating more than 1.5moa from actual in 30 @100yds (siii10-50, nxs8-32, vortex viper6-24)

My initial thoughts were that maybe it was designed as inch increment scope and somehow that factor had been twice applied, but i think that would work the other way and require greater turret increment adjustment

Anyways I do like the optics and would probably purchase anyways but would be happier to hear from users whose scopes were tracking closer to the actual.

 

[Bart B.]

I don't shoot bullets on paper measuring scope adjustment values. More precise results are had by hard mounting adjustment-zeroed scopes focused on a yardstick 100 yards away that's at right angles to the line of sight. Or a mirror 50 yards away reflecting back to the tape measure under the scope.

Move an adjustment 20 major units away from the zero reference on the yardstick. The reticle should be 20.000 or 20.944 inches away, depending on the MOA version it's made for. Easy to discriminate with 30+ power scopes.

 

[Crosshair1]

Just to clarify , i dont have the scope that was tested available to me any longer.
I was just querying if the same could be expected from all scopes of this model, prior to making a purchase of a new one.
Bart, i do take your point that the only true method of testing is as you have described.

 

[Rob01]

No that is not normal for that scope.

 

[Crosshair1]

Thanks guys for the replies, I have one ordered and will update once ive had a chance to test it.

 

[jawjaboy]

The reason for asking is that i've previously carried out a tall test on a buddys ecr1 type and found that turret moa were approximately 9% larger than actual.

I'm running a GE ecr-1. Now that you mention it, that might explain why I see a consistent difference between my ballistics program's come ups versus actual on target. My actuals are always less than calculated and about the 9% you observed.

 

[Bart B.]

I would probably bet a thick dollar bill stack that less than 2% of all internally adjusted scopes equal or better a 2% error across all makes and models for claimed amount per click.

 

[Crosshair1]

To Conclude

Finally received delivery of new SCR Golden Eagle.
Ive fabricated a fixed mount to test the scope off the gun and set up distances with tape measure.
It over adjusts by approx 3.8% on this one so that is quite a difference from the previous one that i checked.
Overall happy with the result.
Thanks to those who replied.

 

[Bart B.]

To Conclude

Finally received delivery of new SCR Golden Eagle.
Ive fabricated a fixed mount to test the scope off the gun and set up distances with tape measure.
It over adjusts by approx 3.8% on this one so that is quite a difference from the previous one that i checked.
Overall happy with the result.
Thanks to those who replied.

Thanks for sharing what you learned.

If the new and old one are the same model, this is proof that normal tolerances in lenses are the main cause of the spread.

The mechanics are the same across all the same model but can have a fixed error based on adjustment thread pitch and actual movement per click. Usually a smaller percent of total error per click.

This is normal for all scopes. The error average and spread will be different across a given make/model.

Someone with a scope spec'd at true trig MOA clicks measured it to see if a full 10 MOA change moved the reticle 10.472 inches at 100 yards would be nice to see. 10.500 would be close enough with a .027% error.

I understand ones reluctance to test their scope to see what errors exist.

 

[dstoenner]

I have been watching this thread in interest. As an engineer I knew that the gun, the ammo and the scope is a system and has to be calibrated as such. years ago, even before I had heard of this tall target test, I had done that test when I was considering going to start shooting F-Class even at 600 yards. The problem is that we don't have a means of inputting the calibrated value into the ballistic program.

The first scope I did this for was a Millet and found it was not MOA but really 1/8 inch per click and it was close. It was so long ago I don't remember how close. My Sightron 8-32 was truly MOA and again it was with in a few percent. My latest scope is a Nightforce NXS 8-32. I have the tall target right here with me so I can be specific. 1 rev is 10MOA on my scope so each REV should go 10.472 inches. First rev was 10.875, second rev was 21.5 and third REV was 31.875. This was measured to the center of 3 shot groups.

What this tells me is that what my ballistic program says and I input it, I will be within 1 to 2 clicks of being right at 1000 yards. My cold clean first fouling shot it always high and the 2nd is usually in or close to the 9 ring. I am happy with what I calculate to be a 1% error.

David