1000 yard problem

Discussion in 'Long Range Scopes and Other Optics' started by Perry, Jun 24, 2012.

  1. Perry

    Perry Active Member

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    I tried shooting at 1000 yards for the first time the other day. I thought that my setup would give me plenty of elevation adjustment in my scope, but I ended up running my elevation to the max and using 3 additional mils of elevation ( using my mil dot as a crosshair.)
    I am shooting a Savage 10FCP in .308 with a Ken Farelle 20MOA base and a Vortex Viper 6.5-20X44.
    I'm running 178gr A-maxes at about 2650.

    Anybody have any idea what I need to fix?

    Thank you
     
  2. LouBoyd

    LouBoyd Well-Known Member

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    The drop of a 178 Amax @ 1000 yards @ 2650 fps is 39 MOA at sea level relative to a 100 yard zero.

    the Viper 6.5-20x44 scope specs say it has 68 MOA of elevation adjustment. Half of that (34 MOA ) should be available without the 20 MOA base. That alone should be within 5 MOA of sufficient adsjustment. With the 20 MOA Farrel base you should have 15 MOA to spare.

    Are you sure your Ferrell base is 20 MOA? Farrell clearly marks the amount of wedge on each base. A flat base would give the results you're seeing. The base should also be marked that it's for a Savage action. What is the part number on the base?

    Other possibilities:
    The scope bell is sitting on the barrel because the rings are too low.
    the range was closer to 1250 yards (not likely)
    The MV was closer to 2350 fps (not likely)
     

  3. FEENIX

    FEENIX Well-Known Member

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    +1 on LouBoyd's response! Please don't take offense but don't want to assume anything or pretend it is impossible but make sure that if it is a 20 MOA, that it is not installed backwards.
     
  4. Bullet bumper

    Bullet bumper Well-Known Member

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    Something funny going on . Vortex says 65 MOA total elevation adjustment 32.5 MOA below the center .
    The 178 A max at 2650 sighted at 100 yards would need around 39 MOA of elevation at sea level at 1000 yards . With 20 MOA on the rail that would leave only around 19 MOA to put on the scope . I agree with LouBoyd the base may not be tapered at all or tapered the wrong way .
    If you measure the length , height at the front and back from the top to where it sits on the action in Imperial I can calculate the taper angle .
    For a 6 inch long rail it should be .035 diffrence between front and back.
    For a 7 inch .041 diffrenece , plus and minus a thou or two as not all rails are exactly the correct MOA.
     
    Last edited: Jun 24, 2012
  5. Perry

    Perry Active Member

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    I was shooting at a 1000 yard shooting range,so I'm pretty confident about the distance. The cases have 43.5gr of Varget in them and I did chrono the load.

    I bought the rifle with the base already on it. Everything looks good as far as the base is concerned. It is 20MOA and installed correctly.
     
  6. FEENIX

    FEENIX Well-Known Member

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    Perhaps the scope does not have the actual elevation adjustment as advertised.
     
  7. Bullet bumper

    Bullet bumper Well-Known Member

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    What kind of rings or mount system do you have on the rail ?
    Did you measure the rail specs ?
    Try this, center the elevation turret by screwing it all the way in one direction gently feeling the end of adjustment point don't over screw it . Then screw back 130 clicks or you can count the clicks all the way from right up to right down and click halfway back to center . Then add 19 MOA of elevation and shoot at 1000 , make sure you are screwing it the right way and adding elevation and not subtracting it . That should put 39 MOA on the gun . The POI should come at least close at sea level and maybe be high at higher altitudes.
    I got a feeling you are screwing the elevation knob the wrong way . The base added 20 MOA and you subtracted a whole lot of MOA and then accounted for it with a 3 Mil of hold over on the Mil dot reticule . 3 mil at 1000 is 9 feet of hold over .
     
  8. Perry

    Perry Active Member

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    I have TPS low steel rings. I will measure the base this evening.
     
  9. green 788

    green 788 Well-Known Member

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    If the base is indeed a 20 MOA base... and there's nothing wrong with the scope...

    the next likelihood is that you have too much windage dialed in.


    What most folks don't realize is that the more you dial the windage to either side, the less "headroom" you have for elevation. Instead of having a full range of motion between 12 and 6 o'clock, you're only able to move the erector between, say, 2 and 4 o'clock before you bump the inside of the scope tube with the erector.

    Very common issue, especially with the windage adjustable rear bases, or with screw holes drilled off axis with the receiver/barrel.

    For those who do have windage adjustable rear bases, you need to center the windage turret, then rough the windage in with the adjustments on the base.

    If you suspect you have your windage dialed too far to one side, just count the clicks to extreme right then extreme left, and see how far off center you are.

    Dan
     
  10. sp6x6

    sp6x6 Well-Known Member

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    Most rail systems dont have a windage adjustable base.
     
  11. orch

    orch Well-Known Member

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    hey there,

    i have a savage action that always gives me the same problem no matter what barrel i put on it, what scope i put on it, etc... it always puts me at the top half of my scope adjustment when i have the particular round i am shooting at the time zeroed at 300yrds...

    i have always had 20moa nightforce 2 piece bases on this action and when my 308 barrel is on said action and i am using my zeiss 3-9 (66moa total elevation available)
    shooting to 1030yrds (needs 36 moa from my zero to make it there) i was always finding myself about 6moa or so short....
    i basically went through all the stuff everyone here has been recomending to you and ruled every thing out and came to the conclusion that i had an action that is either slightly warped or the machining of the top of the receiver is not flush and has a taper or step making it high in the front causing about 30 moa of reverse cant....
    if there is a step or the receiver is warped making the front mounting point higher then needed, there shoud be a noticeable gap between the base and the receiver at the back mounting point if you just have the front mount screws screwed in... if that is the case you could glass-bed the back of the mount to fill the gap and that should get you back to 20 moa correction in your mount (this will also help reduce any torquing in the scope mount and scope when you tighten down the rear screws)

    if there is an actual reverse taper in the action then you are probably gonna want to get a more aggressive scope mount to correct for it... 40 moa should get you there...

    since i have 2 piece bases i corrected my problem by just shimming the rear scope mount with pieces of a beer can (i know i'm cheap :rolleyes: ) and let my burris z-ring inserts copensate and prevent torquing the scope... i didnt have any z-ring offset inserts at the time but thats another route i could have gone to fix my problem....

    anyways.... just saying if you run through all the other good advice everyone else is giving you and you still have the problem then it could just be an out of speck action...

    orch
     
  12. Bullet bumper

    Bullet bumper Well-Known Member

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    That is right Vortex Viper PST and Razor don't limit the windage and elevation to a square track like some scopes do to avoid this . However this scope is a Viper so I am not sure as it is made ina different palce to the other more expensive scopes. If the windage is that far out of center to stop him zeroing at 1000 with 20 MOA on the rail then something would have to be very out of line , in the mount system . He should only need an extra 19 MOA to zero but never say never .
    Is it also possible that the two rings are not matched in height . A low ring at the back and a higher one at the front negating the 20 MOA rail ?
     
  13. Bullet bumper

    Bullet bumper Well-Known Member

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    It is quite possible you are right but I have not got to that yet still trying to work out if the rail is right and the rings are right once we know they are straight and the right heights then that is the next step , suspect the action or even the barrel straightness .
     
  14. bruce_ventura

    bruce_ventura Well-Known Member

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    Perry and Orch likely have the same problem. The barrel is probably mounted crooked in the receiver. This is not uncommon in production rifles. I have a Savage 25 that has the barrel off about 12 MOA to the left.

    When the barrel is cooked to the side, it's easy to confirm using a straight edge along the side of the receiver. When it's off up or down, the stock has to be removed to measure the misalignment between the barrel and the receiver.

    I recommend either swapping bases for a larger bias (30-40 MOA) or using Burris Signature rings with offset inserts.