Leupold scope tracking

[7mmSendaro]

My dad has a Leupold VXIII 6.5-20X50LR on his 6.5WM Sendero. A few weeks ago it suddenly started making on half adjustments on the vertical. For example, a 3MOA adjustment only moved point of impact 3" at 200 yards. This is a 1/2 MOA gun. We could recreate the error over and over again. We sent the scope back to Leupold with a very detailed description. After three weeks they sent it back with a note saying nothing was wrong with the scope. Dad called them and they insisted that it had been thoroughly checked and "everything is fine."

Today I remounted the scope, locked the gun down and did a grid test. I only ran a vertical test due to time restraints.

MOA on scope \ Crosshair movement at 100 yards
0 \ 0
2 \ 2
4 \ 4.3
6 \ 6.75
8 \ 9
10 \ 11
12 \ 13
14 \ 15
15 \ 16.2
Return to zero \ Zero returned perfectly
-2 \ -2.2
-4 \ -4.5
-6 \ -7
-8 \ -9.0
-10 \ -11.5
-12 \ -13.8
-14 \ -16
-15 \ -17.0

I did this test twice and it repeated exactly the same. The decimal values are simply a visual estimate based on the grid.

Before we call Leupold back I want more opinions, being new to LRH. Is this the best you can expect from this scope? Seems pretty bad to me. /ubbthreads/images/graemlins/mad.gif

Thanks for your thoughts.

 

[CatShooter]

The only scopes that I have tested that were 100% accurate was the MK4-M3, and the 3.5-10x40 M3-LR.

These are both military scopes, and you pay for it.

All the others I have tested have a slight tracking error.

You did not say how much it moved at 100yds - 1 moa is equal to 1.05" inches at 100 yds, so 15 moa will give you 15.75" of travel at 100yds.

.

 

[craigp40]

Exactly my thought Cat. Did you measure Scope MOA to MOA Movement or Scope MOA to Inches Movement? If your measurements are in Inches, although it's not perfect I think you're fairly close, especially if you're gun has +/- 1/2MOA error.

 

[7mmSendaro]

The numbers on the left are teh MOA dialed into the scope. Teh numbers on the right are inches of crosshair movement at 100 yards. I understand that 1 MOA is actually 1.047 at 100 yards. Even given that, there is over 1 MOA error at 100 yards.

Thanks for your insights. Kepp em coming! /ubbthreads/images/graemlins/grin.gif

 

[davewilson]

the value in inches you move the crosshairs is only 1.047 for the first minute. each minute after that moves slightly more than the previous. the most important thing to me is that it moves the same each time.this is why i shoot every 100 yards to make a drop chart.then you know how many clicks it is to a given range, under verified conditions.

 

[jwp475]

[ QUOTE ]
the value in inches you move the crosshairs is only 1.047 for the first minute. each minute after that moves slightly more than the previous. the most important thing to me is that it moves the same each time.this is why i shoot every 100 yards to make a drop chart.then you know how many clicks it is to a given range, under verified conditions.

[/ QUOTE ]

A minute of angle is a minute of angle,and remains 1.047" per hundred yards for ever.If your scope adjusts in MOA then every MOA correction will be moving the reticle 1.047" per hundred yards. Some scopes adjust in inchs per hundred yards and that will make a difference. If you need 20 MOA corection at 1K then you need 80 clicks if your scope adjust in MOA if yougo 80 clicks with a scope adjusting in Inchs per hundred yards then you will be 9.4" low at 1K

 

[BountyHunter]

Not all scopes are accurate with what they post on the dials and information.

You need to set up a yardstick or some other device at 100 yards, move x number clicks and actually measure the amount the crosshair move. You can then figure exactly what the click value is for that particular scope. That is fairly common issue in LR shooting.

you will have to lock the gun tightly down to make sure all you move is the crosshair.

Dan Lilja has written articles on this and how it was common for most scopes to actually not move .250 inches, but maybe .268 for example even if it said 1/4 inch or MOA.

 

[CatShooter]

[ QUOTE ]
Exactly my thought Cat. Did you measure Scope MOA to MOA Movement or Scope MOA to Inches Movement? If your measurements are in Inches, although it's not perfect I think you're fairly close, especially if you're gun has +/- 1/2MOA error.

[/ QUOTE ]

I was setting up long range rifles for practical field matches (PC for sniper match rifles)... the scopes are set up so 100 yds is at the bottom of the elevation turrets... so you get lotsa "up"

Then I check the bubbles for cant and the spindles for tracking errors.

I took a 20"x60" craft paper with a straight line down the middle, and a red stickie dot on the bottom.

I tacked the target on the frame and checked with a plumb bob so the straight line was perfectly plumb to gravity.

Then I shot a group at 100yds at the bottom red stickie dot on the target. (Group was centered on the dot).

Then I cranked in 40 moa of up, and I held on the red stickie dot (bottom target) same as the first group.

The second group had to be on the plumb line, or there was a spindle problem, or a bubble problem.

The groups were 42" above the red dot.

I don't work in inches - only moa (1.047")

I've never had a general hunting scope pass this test.

.