Size of target at 800 yards? And how close to center?

Discussion in 'Long Range Hunting & Shooting' started by sdriverbottom, Oct 7, 2013.

  1. sdriverbottom

    sdriverbottom Well-Known Member

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    Hey guys I'm wondering what size target your shooting at 800 yards and also how far off-center are your groups at that 800 yards?? I've been shooting half minute groups but I'm off Center at 800 yards about 5 inches left and 4 inches high. I know someone will say move 5 inches to the right and 4 inches low. I don't know if I can shoot that consistent each time at 800 yards. I guess this is why I'm wondering how close you guys stick them to around Center?? Thanks!
     
  2. MMERSS

    MMERSS Well-Known Member

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    Scope cant and tall target test. Look it up in the Google custom search located in the upper right corner. This may help if not already conducted.
     

  3. el matador

    el matador Well-Known Member

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    You should be able to dial in the elevation by making adjustments within the calculator. For windage there could be a few things at work. Spin drift at that range could be pushing you several inches to the right (assuming RH twist), meaning your line of sight is actually 8 inches off or thereabouts. A 2mph crosswind will make your bullet drift that much, and it's hardly even perceptible if you're not paying close attention.
     
  4. WildRose

    WildRose Well-Known Member

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    Consistent errors are always the easiest to solve. Check the data you are feeding your ballistics calculator.

    Personally I'd say sight in at 800 and work it back reversing your drop chart and then see where you end up when you get back to 100yds.

    There's a slight possibility that it's "driver error" but being this consistent makes that less liikely.

    What size groups are you getting at 100? 200? 800?

    Generally I'll shoot at a 2MOA target for the given range using a small bull that can easily be distinguished.

    If you aren't getting at least 2MOA then we've got a lot of possibilities.
     
  5. Greyfox

    Greyfox Well-Known Member

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    I will try to shoot at a target that provides an aiming point that is .5-1MOA in size. I agree with prior posts that a tall target test is important, not only for cant, but also for determining actual click value. I will center exactly for elevation and be sure to enter either the correction in my ballistic calculator for true velocity, or actual click value if my scope turret is not .25 click value. Either will do but if tour turret is off your velocity will not be true. This will keep my zero. For windage, I will generally rely on my tall target test, and confirm on a windless day making sure to take spin drift into account. It has almost always been on if my tall target test and scope alignment was good. I wil always try to center my groups at my maximum shooting range.
     
  6. sdriverbottom

    sdriverbottom Well-Known Member

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    Wildrose - my groups are good at 100 and 200 yards as well.

    My height isn't as much of a concern for me as I was 4 inches high, chart called for 14.3 Moa I dialed to 14.5 and should have done 14.25..2 inches in error there.

    I think I'm going to try the tall target test (did it for turret validation clicks couple years ago) to see it there's a cant. When I mounted my scope I used the wheeler leveling kit an also a rope with a cinder block hanging from a tree to try an make sure the reticle was level. I do have a level on my gun I level before each shot currently.

    During the tall target test, do you place the reticle to be directly on the vertical line you draw? If ur scopes level they should match up? The paper obviously needs to be level/straight on the board to validate than as well right? Now if you notice the sting working to the left of the line do you just move the crosshairs right or does your scope need to be remounted?

    Thanks for all the info guys! I really would like to get left and right dialed in better at distance.
     
  7. sdriverbottom

    sdriverbottom Well-Known Member

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    At 100 yards hitting directly above center maybe isn't a good indication of left or right at longer distance? Bullet hasn't stabilized? Maybe why I'm seeing that group at 800 left?
     
  8. MontanaRifleman

    MontanaRifleman Well-Known Member

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    When you used your improvised plumb bob, did you align your scope reticle AND bore of your barrel? If you didn't, your bore might be aligned left or right of your scope.

    When I align mine that way, i remove the bolt and line up the bore to center on the plumb bob line... then I adjust the scope reticle to the line to get both of them in the same vertical plain.
     
  9. sdriverbottom

    sdriverbottom Well-Known Member

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    Guys check my level and this is what I found. Pics attached.

    My level on my scope is cant a bit vs the level on my rifle. With that if I'm understanding the tall target test method. I would have my rifle cant a bit to the right so it seemed level, as I would shoot at 800 yards not knowing I tilted the crosshairs to the right to make it level but that affected my boreline to crosshair alignement. My cross hair went up and right an that made the barrel point more left, and this would be why my hits were left on target?

    I hope I understood all your guys information and this is the fix.
     

    Attached Files:

  10. sdriverbottom

    sdriverbottom Well-Known Member

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    Pic
     

    Attached Files:

  11. WildRose

    WildRose Well-Known Member

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    Looks to me like you need to rotate your scope just a few degrees to the right to get the vertical CH aligned with the center of your bore.

    Before doing that though I'd set up a plum bob and look at your vertical CH compared with it while your rifle level shows to be perfectly level.

    The easiest way I know to set it up is with a large piece of construction paper (think grade school project construction board) drawing a thin vertical line using a 4' carpenter's level.

    As for getting exactly centered (scope and bore alignment) that is most easily done with a laser boresight.

    Once you are level, then set it up with the boresight at 100yds or further if you can get a good image farther, and then move the windage until they align.

    Of course as soon as you start shooting that's going to change but at least you start off perfectly aligned.

    That's one thing I favor about the old style Leupold and Redfield one piece mounts where you could adjust the windage with the set screws for initial bore sighting.
     
  12. MontanaRifleman

    MontanaRifleman Well-Known Member

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    One thing I just thought of is if the cinder block isn't hanging from it's center of gravity, it will cant the rope. Maybe that's the problem? I use an actual plumb bob on a string. That's why carpenters use plumb bobs instead of 2x4's or whatever.

    Also, IMO, setting up the rifle as close to the string as the scope will focus it on lowest power is the easiest and most accurate way of doing it. A lazer bore sight would be good if you have one but if you don't, it's fairly easy to eyeball the bore's center. It has always worked good for me.
     
  13. WildRose

    WildRose Well-Known Member

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    "Poster Board" is what I was trying to think of, or for that matter just a large piece of cardboard, but the white poster board would be easier to use to make your vertical line easier to pick up.

    Just set the target up, and then use a carpenter's level to draw your plum line. Using this method will eliminate any chance of wind blowing your plum bob off level.
     
  14. sdriverbottom

    sdriverbottom Well-Known Member

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    This might be a stupid question but I have seen this on one of the long range hunting shows..they put a cant in the scope to take out spin drift. With now when my action is level as pics showed my crosshairs off center counter clockwise a bit (so there moving down and right when dialing long range) With my cross hairs off counter clockwise I offset that by rotating clockwise to level on my scope. This in turn rotates my level bore to cant clockwise ( when I shoot with that set up my hits are left of target, does that seem right with impacts??

    Because what I'm wondering for the time being level my action ( scope is cant counter clockwise) move my level on my scope to match my bore..so spin drift is to the right but scope is offsetting that with it mounted counter clockwise and moving up and left, then maybe the bullet meets in the middle??

    Thought it was worth asking since I'm sure I saw it once, then during offseason get things squared up.
     
    Last edited: Oct 9, 2013