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Given this information what would you do

Discussion in 'Rifle Country' started by daniel craig, Nov 29, 2020.

  1. daniel craig

    daniel craig Member

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    Given this information and the fact that I plan on going to a 25 yard range I’m thinking if I sight in at 4 inches high at 25 I’ll be within 6 inches of where I’m aiming out to 400 yards....


    Assuming I’m reading this correctly...

    that settles it. I’m a dummy. 50mm NOT 5.0 inches. 50mm is roughly 2 inches.
     

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    Last edited: Nov 29, 2020
  2. gotboostvr

    gotboostvr Member

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    That didn't sound quite right to me, so I plugged your info into a calculator and set it for a 400yrd zero.

    full&d=1606670988.jpg

    So assuming all your info is correct (4" sight hight? ) it looks like you should be about 1.4" low at 25yrds for a 400yrd zero.

    I used http://www.shooterscalculator.com/ if you want to play around with it yourself.
     
    Last edited: Nov 29, 2020
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  3. ECVMatt

    ECVMatt Member

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    I would be real careful with a printed chart. You need to get out and shoot at distance to confirm that the chart is correct. The chart posted by gotboostvr looks correct to me.
     
  4. wiscoaster

    wiscoaster Member

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    Your optic's sight axis is four inches above your bore axis? Something doesn't look right there in your inputs. What kind of rifle is this?
     
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  5. daniel craig

    daniel craig Member

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    4 inches high was about all the hornady calc let me put in. It’s closer to 5 though.
     
  6. gotboostvr

    gotboostvr Member

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    I've mentioned in a few threads lately that I've been pouring over ALOT of ballistic tables lately, and that just sounded a little off.
     
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  7. daniel craig

    daniel craig Member

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    Problem is I don’t have access to a 400 yard range and the place I’m hunting doesn’t like target practice during the hunting season.
     
  8. gotboostvr

    gotboostvr Member

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    How are you measuring that? Most bolt actions are closer to 2 I belive.
     
  9. daniel craig

    daniel craig Member

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    It is pretty close to that. Sporterized milsurp rifle.
     
  10. wiscoaster

    wiscoaster Member

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    OK. 2.5 inches is typical for an AR platform, that's why it leaped out at me. I don't have scopes on any of my milsurps, and I usually plug in 1.5 inches to run a table on them with iron sights.
     
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  11. wiscoaster

    wiscoaster Member

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    I ran a table out to a 400 yard zero using my usual calculator and came up with this:

    Screen Shot.png

    As you can see, I also could not use an offset over four inches. I think the easy-math way to compensate for that would be to subtract one inch from the first line and then reduce that subtraction by one-sixteenth of an inch for each succeeding line. This would put your first zero somewhere a little short of 50 yards. So if you're zeroing for four hundred yards, get in the ballpark first on the 50 yard range then fine tune on the 400 yard range. That's how I'd do it, anyway. Though sometimes you get out there and find yourself scratching your head wondering what you're missing about your setup. :oops:
     
  12. army_eod

    army_eod Member

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    Use a good calculator and know your muzzle velocity.
    You will need a chronograph. Period.
     
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  13. daniel craig

    daniel craig Member

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    I know what I NEED it’s a simple matter of what I have at hand.
     
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  14. gotboostvr

    gotboostvr Member

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    PREACH.
     
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  15. army_eod

    army_eod Member

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  16. jmr40

    jmr40 Member

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    If the best you can do is a 25 yard zero then do what you have to do. But I'd not trust that much past 100 yards. You might be close enough to be on paper at longer ranges with a 25 yard zero. But I wouldn't guarantee close enough to feel comfortable shooting game. I'd not pull the trigger on a game animal at a range that I'd not actually shot and verified at that range. For one thing a tiny error in zero at 25 yards is easy to make without realizing it. If you're off by 1/4"( less than the diameter of most big game bullets) at 25 yards that translates into several inches at 400.

    You really need to get this done long before hunting season.
     
  17. herrwalther

    herrwalther Member

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    150gr at 2840FPS? Is this a Mosin 91/30? The numbers match except for the sight height. I have seen several scope mounts and not many were 5 inches above bore. Even setting up a scout scope with very long eye relief would be more accurate than a scope sitting 5 inches above bore.
     
  18. ECVMatt

    ECVMatt Member

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    I have been in your situation and get it. Having said that, 400 yards is a long ways to shoot at an animal without a lot of practice. I hunt out west where we can get long shots and rarely have had to take a shot over 300 yards.

    The problem with a 400 yard zero is that if you misjudge an animal at your mid-range trajectory, you will shoot over them.

    I have used the maximum point blank range zero for most of my life and have yet to miss an animal because of hold over or possibly hold under with a 400 yard zero.

    This could be helpful in finding your MPBZ:

    http://www.shooterscalculator.com/point-blank-range.php

    I would strongly advise against shooting at game at 300 + yards without some form of practice. If you don't have a range that allows for that distance, then pass on it for this year and come up with a plan for next year. If you still think that you are up to the task, I would spend as much time as possible looking at the game animal you are hunting between 200 to 400 yards. Often it is difficult to confirm whether or not it is legal to shoot, if that is a requirement, without additional, expensive equipment.

    Best of luck,

    Matt
     
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  19. gotboostvr

    gotboostvr Member

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    Just covering all the bases, you DO know sight over bore height is the distance between the MIDDLE of the scope and the MIDDLE of the bore correct?
     
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  20. daniel craig

    daniel craig Member

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    Great advice! Realistically I probably won’t shoot at over 100 but I was curious what the info would be like further out.
     
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  21. daniel craig

    daniel craig Member

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    I thought it was from bottom of bore to top of scope? ;)
     
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  22. gotboostvr

    gotboostvr Member

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    ;)
    No offense intended, just making sure we're all on the same page. I'm kind of interested in what this set up looks like.

    Fyi, the Shooterscalculator.com page will let you punch in whatever you need for sight height. I just tried 5.9" for gits and shiggles.
     
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  23. daniel craig

    daniel craig Member

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    I didn’t go into the season like this. I jarred the scope pretty hard though so I’m concerned.
     
  24. Bfh_auto

    Bfh_auto Member

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    The easiest way to measure is. Diameter of bolt divided by 2. Diameter of scope divided by 2. Add the first 2 together. Then add the space between the bolt and scope.
    What scope mount and rifle are you using? Your measurement seems very odd.
     
  25. daniel craig

    daniel craig Member

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    Read my comment. I’m just a dumb ass.
     
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