MOA?

Discussion in 'Long Range Scopes and Other Optics' started by joseph, Mar 25, 2010.

  1. joseph

    joseph Well-Known Member

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    How many inches is 65 MOA?

    joseph
     
  2. TH

    TH Well-Known Member

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    It depends on a lot of things. 1 MOA at 100 yards is 1 inch. 1 MOA at 600yards is 6 inches. 1 MOA at 1000yards is 10 inches are you following me? When I shoot a mile with my 6-284 rifle with a 107 grain bullet at 3400 fps it takes 56MOA for the bullet to get there. If i shoot my 338-408 at 3300fps and a 300 grain smk it takes 42 MOA to get there. The difference is how flat a rifle shoots at a mile. lets say you are shooting at a 600 yard target that is a 12X12 square. I see your bullet impact 12 inches low and 6 inches to the left im going to call a correction of 2 MOA up and 1 MOA right. This makes for quick corrections when you ard dialing the MOA into your scope.
     

  3. TH

    TH Well-Known Member

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    So 65 MOA at 100yards is 65 inches. 65 MOA at 200 yards is 130 inches. 65 MOA at 500 yards is 325 inches.
     
  4. joseph

    joseph Well-Known Member

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    The drop chart for my bullet is 73" at 600 yards and 286" at 1,000 yds. My scope has 65 MOA of adjustment. Does this mean that I can use a flat Picatinney rail?

    joseph
     
  5. LRSickle

    LRSickle Well-Known Member

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    Maybe not. When the scope manufacturer says 65moa adjustment they mean from top to bottom. After you zero you rifle you'll be somewhere in the middle. You might be closer than 28.6moa, (29.97 real moa) to the top of your adjustment and in that case your SOL for 1000 yard shots.
    Get a ramp just so can keep your reticle closer to the middle of your adjustment.
     
  6. Eaglet

    Eaglet Well-Known Member

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    Joseph, a MOA is an angular measurement, stands for "minutes of angle", so 65 MOA = 65 minutes... think of a huge V and let's say that the exaggerated angle in between is 65 MOA. The longer the V it is, the distance between the ends of the v is greater; and the V still has an angle of 65 moa.

    So, we need to specify a distance. Like how many inches holds a MOA AT 775 yards? We know that the true dimension of a moa is: 1MOA = 1.047" at 100 yards. Not 1"; sooner or latter if you use 1" it will get you in trouble and I will show you later.

    So, if every 100 yards I have a distance of 1.047, at 775 yards you would have (1.047 x 7.75 = 8.11 inches. ---- Someone could tell you, hey use 1 inch and that would give you 7.75" (just dividing the distance by 100), close enough! Well it would be for a spotter but it is not always the truth. Let me explain:
    Let's say you have a rifle-scope calibrated in MOA (The Turret), and you make some drop tables that give you the answer in inches (IPHY); and let's say that for a 1000 yards shot the table says you need 39 IPHY which are inches. Now you believe that 1 moa is = to 1 inch and you just use your scope and dial 39 MOA on the turret. The most awesome buck was on your sights and you felt confident but the animal just walks away and you loose a once in a life time opportunity. What Happened???? Well this is what happened:

    You turned the moa turret to 39 which were really 39 MOA and not inches. That means that... (39"/1.047 = 37.25 moa) --- So instead of inputting 37.25 moa on the turret, we dialed in 39 moa. That's 1.75 moas more than needed... CLOSE ENOUGH! ---- NO! IT'S NOT!!! 1.75 MOA at 1000 yards is:
    (1.75 X 1.047) x 10 = 18.3 inches. Your bullet went about 9" over his back!

    IN OTHER WORDS:

    The drop chart in inches told you to dial 39 IPHY (inches per 100 yards) which is 37.25 moa;
    you dialed 1.75 moa more than needed and that equated to 18.3 inches over
    the aiming point missing your trophy.
     
  7. joseph

    joseph Well-Known Member

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    Get a ramp just so can keep your reticle closer to the middle of your adjustment.[/QUOTE]

    What angle ramp would I need? I am planning on getting Kenton Industries to make me new turrets calibrated to my drop chart in yards to coordinate with my laser range finder.

    joseph

    PS: Thanks to everyone for explaining about MOA.
     
  8. Eaglet

    Eaglet Well-Known Member

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    If when mounting the scope on normal flat bases all work as intended, then this is how you play ball:

    First, center the scope turrets dead center for vertical and horizontal adjustments, that means it would only leave you about 32.5 moa of upward adjustment. You do the same with the windage adjustments. If the drilled holes on the action are fairly strait, you should not be too far from the center of the target at 100 yards.

    Depending on your scope height and muzzle velocity, you would loose typically 4 moa to bring the impact point to center of target. That means you would have 32.5 - 4 = 28.5± MOA left of vertical adjustment.

    Now, 286 inches at 1000 yards means (286/1.047)/10=27.32 MOA.

    You need 27.32 MOA to be on target, and you have 28.5 MOA of vertical adjustment left... So it looks like you might; but then again depending on how it goes when mounting the scope your might not, as LRSickle stated.

    Just follow LRSickle's advice, get a 20 MOA picatinny rail and you'll be for sure good from zero to way over 1000 yards.

    Good Luck!
     
    Last edited: Mar 27, 2010
  9. winmagman

    winmagman Well-Known Member

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    Joseph

    Keep in mind that the closer to the top of your verticle adjustment range you get the less room you have for windage adjustment. So even if you can get to 1000 yds with a flat base you will have very little range to adjust for the wind.

    Chris
     
  10. jwp475

    jwp475 Well-Known Member

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    65 MOA at 100 yards is 68.068 inches

    1 MOA is 1/60 of 1 degree of angle

    Eaglet explained it correctly.
     
  11. joseph

    joseph Well-Known Member

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    What angle ramp would I need? I am planning on getting Kenton Industries to make me new turrets calibrated to my drop chart in yards to coordinate with my laser range finder.

    joseph

    PS: Thanks to everyone for explaining about MOA.[/QUOTE]

    Can someone answer this question for me? What degree Picatinney rail should I get? I am shooting a 6mm Norma BR. with Berger 105 gr. VLSs with a 26" barrel with about 2900 fps.

    joseph
     
  12. KRP

    KRP Well-Known Member

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    Can someone answer this question for me? What degree Picatinney rail should I get? I am shooting a 6mm Norma BR. with Berger 105 gr. VLSs with a 26" barrel with about 2900 fps.

    joseph[/QUOTE]

    After zeroing, subtract the available adjustment in the scope from the amount of adjustment needed for the yardage you want to shoot at. If you wind up with a negative number you have enough but may want to put a sloped base on anyway to keep away from the extreme end of the scopes adjustment. Available adjustment is what's left after you zero the rifle not the total adjustment in the scope.
     
  13. joseph

    joseph Well-Known Member

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    "Just follow LRSickle's advice, get a 20 MOA picatinny rail and you'll be for sure good from zero to way over 1000 yards". "QUOTE" lightbulb

    Thanks guys I missed this back up in the other replies. A 20 MOA Picatinney rail it will be.

    "Aim small miss small", :D

    joseph