Box test, tall target, tracking test

[mike a]

I watched Bryan Litz video. I got the math. Here's my question. I'm getting way in excess vertical travel. At 100 yds 15.75" with 14 moa dialed. Windage is good. Is it possible the 20 moa rail could be causing this i.e. reticle not centered? Some kind of curved lens thingy. Optical illusion. Also I dialed from zero down. Wish I had gone up. Mike

 

[Ledd Slinger]

First question. Which scope do you have?

Second question. Did you actually measure off the range with a tape or did you use a rangefinder?

Also possible your scope or reticle moved under recoil.

 

[FatBoy]

I had an old 3.5-15 NXS that moved 4.5" in one spot consistently in a 3moa box test. Just a jacked up section in the scope erector cell. Nightforce replaced it the second time I sent it in.

 

[mike a]

First question. Which scope do you have?

Second question. Did you actually measure off the range with a tape or did you use a rangefinder?

Also possible your scope or reticle moved under recoil.

1st, Sightron 8x32x56. 2nd, With a 100' steel tape x3. I'm with in a few inches of the turrets. 3rd, Scope not moving in mounts, could the reticle be moving, I don't know. 4th, so back to my question, having a 20moa rail and dialing down puts me about 34moa down. I think I'll try it again with the reticle near center.

 

[Ledd Slinger]

1st, Sightron 8x32x56. 2nd, With a 100' steel tape x3. I'm with in a few inches of the turrets. 3rd, Scope not moving in mounts, could the reticle be moving, I don't know. 4th, so back to my question, having a 20moa rail and dialing down puts me about 34moa down. I think I'll try it again with the reticle near center.

Yeah some scopes can have issues at the outer levels of their adjustments. But you shouldnt have 7% error. Best bet would be to get a scope tester with dual rails and confirm the adjustments without recoil against another scope that remains on a single POA. If its confirmed to be off too far I'm sure Sightron will take care of you. Though I don't know what level of error Sightron considers it to be a manufacturing defect...

 

[dkhunt14]

I watched Bryan Litz video. I got the math. Here's my question. I'm getting way in excess vertical travel. At 100 yds 15.75" with 14 moa dialed. Windage is good. Is it possible the 20 moa rail could be causing this i.e. reticle not centered? Some kind of curved lens thingy. Optical illusion. Also I dialed from zero down. Wish I had gone up. Mike

Did you shoot the gun or just click and measure? Matt

 

[mike a]

Did you shoot the gun or just click and measure? Matt

Shot several 3 shot 1/2" groups. I'm going to center the reticle and try again.

 

[Bart B.]

Scope makers don't test their adjustments shooting bullets. Neither should we. You don't need to shoot bullets because all windage and elevation (W and E) adjustments do is change the angle and direction of the line of sight to the line of fire (the bore axis). All we need to do is see if the reticle moves the right amount for some number of W and E clicks. Why add the variables we and our stuff have?

Put a yardstick 50 or 100 yards away, anchor the scope sighted on it then move an adjustment 10 MOA. If the reticle moves 5" at 50 yards (10 at 100), then all is perfect. A 5% error is common because of optical and mechanical tolerances in the scope. If its repeatable, all is good.

Move an adjustment 1 click one direction then back 1 click for backlash. Distance moved should be equal both directions. Then repeat with 2 clicks each way, movements should double. Box adjustments and watch what happens.

Save your ammo and get better data. Look into the scope with a monocular and magnify the image and easily see 1/10th moa errors.

Centering windage and elevation adjustments in their mechanical range does not put all the scopes optics on the centerline axis of the scope. Use the 2V block or mirror method.

 

[Bart B.]

Yeah some scopes can have issues at the outer levels of their adjustments. But you shouldnt have 7% error.

Where's the 7% error?

15.75 is about 12.5% more than 14.

 

[Ledd Slinger]

Where's the 7% error?

15.75 is about 12.5% more than 14.

You're not paying attention.
He said his impacts were 15.75 "inches" high with 14 MOA dialed. Not 15.75 MOA high. Nobody measures MOA on impacts of a tall target test. That would be a pain in the ass. You measure the impacts in inches and do the math.

14 MOA = 14 x 1.047 = 14.658" @ 100 yards

15.75" ÷ 14.658" = 1.074 = 7.4%

 

[Bart B.]

Yeah some scopes can have issues at the outer levels of their adjustments.

Most will continue to click up or right after the reticle has stopped moving. The inner tube as at its mechanical limits but the adjustment still has a way to go before reaching its limit.

 

[Ledd Slinger]

Most will continue to click up or right after the reticle has stopped moving. The inner tube as at its mechanical limits but the adjustment still has a way to go before reaching its limit.

On cheap optics I suppose that might be true. My reticles move until the very last click where the turret stops solid.

 

[Bart B.]

You're not paying attention Guffey.
He said his impacts were 15.75 "inches" high with 14 MOA dialed. Not 15.75 MOA high. Nobody measures MOA on impacts of a tall target test. That would be a pain in the ass. You measure the impacts in inches and do the math.

14 MOA = 14 x 1.047 = 14.658" @ 100 yards

15.75" ÷ 14.658" = 1.074 = 7.4%

You're not using the shooting sports MOA standard, yeffuG.

15.75" divided by 14 MOA/inches is 1.125 or 12.5%.

You need to use at least 50 decimal places if you want to be closer to exact in trigonometry. 3 places is sloppy.

 

[mike a]

You're not paying attention.
He said his impacts were 15.75 "inches" high with 14 MOA dialed. Not 15.75 MOA high. Nobody measures MOA on impacts of a tall target test. That would be a pain in the ass. You measure the impacts in inches and do the math.

14 MOA = 14 x 1.047 = 14.658" @ 100 yards

15.75" ÷ 14.658" = 1.074 = 7.4%

Yes, this the math I used. From the Litz video on YouTube. I got 15.75 inches of impact shift with 14 moa dialed.

 

[mike a]

Scope makers don't test their adjustments shooting bullets. Neither should we. You don't need to shoot bullets because all windage and elevation (W and E) adjustments do is change the angle and direction of the line of sight to the line of fire (the bore axis). All we need to do is see if the reticle moves the right amount for some number of W and E clicks. Why add the variables we and our stuff have?

Put a yardstick 50 or 100 yards away, anchor the scope sighted on it then move an adjustment 10 MOA. If the reticle moves 5" at 50 yards (10 at 100), then all is perfect. A 5% error is common because of optical and mechanical tolerances in the scope. If its repeatable, all is good.

Move an adjustment 1 click one direction then back 1 click for backlash. Distance moved should be equal both directions. Then repeat with 2 clicks each way, movements should double. Box adjustments and watch what happens.

Save your ammo and get better data. Look into the scope with a monocular and magnify the image and easily see 1/10th moa errors.

Centering windage and elevation adjustments in their mechanical range does not put all the scopes optics on the centerline axis of the scope. Use the 2V block or mirror method.

Bart, as I said I'm going to center my reticle "mirror" and try it again, however I like your input also and will give it a try. Problem is getting the scope in a stable setup. Mike

 

[Bart B.]

Yes, this the math I used. From the Litz video on YouTube. I got 15.75 inches of impact shift with 14 moa dialed.

Then your scope moves impact 1.125 inches for a 1 MOA adjustment on the scope. Another scope the same make and model may move bullet impact 1.063 inches per 1 MOA adjustment.

 

[mike a]

Then your scope moves impact 1.125 inches for a 1 MOA adjustment on the scope. Another scope the same make and model may move bullet impact 1.063 inches per 1 MOA adjustment.

And this value is more or less the whole reason for the test. My Ballistic AE program asks for turret value. 1.125 sounds good.

 

[Jimmy James]

I've box tested the SIII 6-25x50 and the 8-32x50 and never seen that much error or what ever you want to call it. Mostly use the 100yd "precision" target with 1" squares all over, 4 shooting boxes and the center diamond. Will start at the btm left shooting box target and go up 12, right 12, dwn 12 and left 12. Usually the 5th shot is touching the 1st shot. I never thought to measure the vertical point of impact. Call Sightron and ask Alan.

 

[Bart B.]

A few percent spread in a given make/model scope's front objective lens focal length will cause the same spread in adjustment value per unit across all of them.

 

[Bart B.]

Nobody measures MOA on impacts of a tall target test.

I've never shot bullets doing a tall target type test.

There are ways to verify a scope's elevation adjustment plane intersects the barrel's bore center axis (line of fire) without firing a shot. But you first have to verify the vertical reticle axis tracks the elevation adjustment plane.