Vortex Maxed Out Elevation Problem?

Discussion in 'Long Range Scopes and Other Optics' started by JW74, Mar 30, 2015.


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  1. JW74

    JW74 Well-Known Member

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    I was out shooting my Savage 11 LRP in 6.5 Creedmoor yesterday. This was the first time going out over 800 yards. I went out to 1200 yards and the estimated come up was 11.5 Mills from a 100 yard zero. I ran out of adjustment at 9.5 Mills. The scope is the Vortex Viper PST FFP 6-24x50. It has 19 Mills of internal adjustment. I have a 20 moa base and it is zeroed at 100 yards. Is it common to use 9.5 Mils of my elevation to zero the scope at 100 yards leaving only 9.5 Mils left for elevation adjustments? I ended up having to use 2 Mills holdover to make my shots. I was hoping to get out past 14-1500 yards eventually but am afraid this scope and base set up wont make it. Any help is greatly appreciated.

    Also shot my .308 Remington 700 at the same distance. Has a 20 moa base with a Vortex VIPER HS LR 4-16X50 FFP. It had plenty of elevation adjustment to get to 1200 yards and being a 308 needed more come up than the 6.5 did. Only difference is the 308 scope is in moa with 68 moa of internal adjustment. Come up at 1200 yards was 43 moa. Elevation above sea level was 6900' with both rounds shooting about 2700 fps.

    Thanks again for the help.
     
  2. JW74

    JW74 Well-Known Member

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    I just double checked the scope. It is mechanically centered for elevation. With a 100 yard zero on a 20 moa base I have 9.5 Mils up adjustment and 10.0 Mils down adjustment. For windage I have 7.5 Mils right adjustment and 11.5 Mills left adjustment from zero but the windage may need to be re-confirmed at 100 yards before I make that an absolute as I was dialing for a 20 mph cross wind yesterday and may have lost track of windage zero.
     
  3. FearNoWind

    FearNoWind Well-Known Member

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    I'm not sure if I fully understand what you wrote but I'll give it a try.
    You have a scope with 19 milrads of adjustment end to end and you have it set at zero for 100 yards with the cross hairs centered in the scope (leaving you with an adjustment of about 9 mils down and 9 mils up).
    Obviously, you can't get more out a scope than it has in it. Setting your 100 yard zero with the cross hairs centered, leaving 9 mils on each side, amounts to wasting the lower end of your scopes capability. I would never recommend working out at the extreme end of any scope's range of adjustment. But if you'll add a 20 MOA rail to that rifle your horizontal cross hair will be on the lower end of the available adjustment in your scope and you'll find that you'll have the adjustment you need to get it on target at longer distances.
     
  4. JW74

    JW74 Well-Known Member

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    Thanks for the reply FearNoWind. The thing is, I currently have a 20 moa base on the rifle already and am still zeroed at the mechanical middle. I too though it would be zeroed closer to the bottom with that base. My next option is to check to see if the 20 moa base needs to be bedded perhaps?
     
  5. kilmer

    kilmer Active Member

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    It might not hurt to mic the base to make sure it is really a 20 MOA base. I can't remember the manufacturer, but I once received a base that was 0 MOA in a 20 MOA package.
     
  6. bruce_ventura

    bruce_ventura Well-Known Member

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    ^^ Easy to check. If that isn't the problem, then either switch to a 30 or 40 MOA base, or use Burris Signature rings.

    FYI, I've seen Savage factory barrels installed crooked by 10-15 MOA. That is likely the problem with your rifle. Fixing that will be expensive.
     
  7. Motocross308

    Motocross308 Member

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    maybe you have the rail 180 degrees off ?
     
  8. JW74

    JW74 Well-Known Member

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    I checked that right initially and it's mounted correctly.
     
  9. Jay Kyle

    Jay Kyle Well-Known Member

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    This is not unusual as most folks don't think about properly sizing the rail. Properly sizing a rail requires considering all factors to maximize dial capability. The premise here is to NOT be in the mechanical center, but near the bottom of the range to maximize dial range.

    1. Consider the max advertised dial range of a scope, which is usually less than the actual dial capability - my preference is to stay within the advertised dial range to ensure I'm in the 'safe' scope tolerance window. This is for both windage and elevation.

    2. Consider any bullet drop between your barrel and your zero distance - typically very little

    3. Consider your max windage adjustment you will need at 100 yds, 200 yards, etc - again staying within the advertised range window.

    3. Consider mount error - e.g. when you zero your scope after mounting it's 3 moa to the left - and how that reduces both the windage and elevation window

    When you do the math and put all of this together you should end up with a rail size that will maximize your safe adjustable range in both windage and elevation. That could be some oddball size like 33MOA - we all know oddball rails don't exist so stay within your tolerances and get one that's as close as you can - it's the best you can do.

    Jay
     
  10. RonS

    RonS Well-Known Member

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    That is what I was thinking. I shoot the same rifle with the same scope and the same 20 MOA base and never run out of adjustment at those ranges.
     
  11. Ol'Gator

    Ol'Gator Well-Known Member

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    Likely installed backwards.
     
  12. JW74

    JW74 Well-Known Member

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    I'll check again to be safe but I'm certain the rail is installed the correct direction.
     
  13. JW74

    JW74 Well-Known Member

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    I am wondering if I should try a different 20 MOA base as possibly the one I have was not an actual 20 MOA base? Is there any way to tell. It is sloped forward like my 20 MOA base on my other rifle.
     
  14. bruce_ventura

    bruce_ventura Well-Known Member

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    Measure the front and back base height with calipers. Then do the math.

    If it were me, I would buy a 30 or 40 MOA base instead of another 20 MOA base.