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Thread: M.O.A. scope base...........education requested.

  1. #1

    Default M.O.A. scope base...........education requested.

    Are there rules of thumb for "NON-Zero" M.O.A. scope base. Are there tables for choosing a 15 or 20 or 25 M.O.A. scope base.....???

    Is there a mathematical formula or a constant ratio that is used for this determination. Or is it trial and adjust, trial and adjust....???

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    Member gunbugs's Avatar
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    No tables that I know of. You will need to know how much elevation you will need for your longest distance you will shoot at. Then you will need to know how much elevation your scope provides when mounted on your rifle, usually with a zero MOA base. Then you can determine if you need the added elevation provided by a "slanted" MOA base. And you can then determine how much more elevation you will need. Most of the "long range" scopes have substantial elevation in the adjustments. The slanted bases will make you start closer to the "down" end of your elevation adjustment, thus providing more "up" travel in the elevation knob.
    "A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind."

  3. #3

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    Thanks.........good explanation.

    Quote Originally Posted by gunbugs View Post
    No tables that I know of. You will need to know how much elevation you will need for your longest distance you will shoot at. Then you will need to know how much elevation your scope provides when mounted on your rifle, usually with a zero MOA base. Then you can determine if you need the added elevation provided by a "slanted" MOA base. And you can then determine how much more elevation you will need. Most of the "long range" scopes have substantial elevation in the adjustments. The slanted bases will make you start closer to the "down" end of your elevation adjustment, thus providing more "up" travel in the elevation knob.

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    Member orion94us's Avatar
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    Quote Originally Posted by gunbugs View Post
    No tables that I know of. You will need to know how much elevation you will need for your longest distance you will shoot at. Then you will need to know how much elevation your scope provides when mounted on your rifle, usually with a zero MOA base. Then you can determine if you need the added elevation provided by a "slanted" MOA base. And you can then determine how much more elevation you will need. Most of the "long range" scopes have substantial elevation in the adjustments. The slanted bases will make you start closer to the "down" end of your elevation adjustment, thus providing more "up" travel in the elevation knob.
    gunbugs is pretty close with his reply.

    If you know your particular calibers BC, and have chronographed your load of choice, you can reliably use a ballistic calculator (use G7 profile to get most accurate data) to figure out how many MOA or Mils of elevation adjustment you are going to need to be able to dial reach a pre determined distance. Then you reference either your current optic or optic of choice if you are looking to purchase a new one and see if it has enough internal adjustment in scope to match your desired shooting solution. Keep in mind that when a scope has listed, say 30MOA of elevation adjustment, that is measured from the bottom of the dial. Meaning that the elevation dial is dialed all the way down. That is where adding a 20 or 30 moa base comes into play. It gets your initial zero adjustment down into the "bottom half" of adjustment and allows for more upward elevation adjustment for longer shots. I you want to get really fancy and reach longer a guy could pair a 20 moa base with a set of Burris signature Zee rings and add in an additional 20 moa by shimming the rings and end up with a total of -40 MOA to start with.

    Be forewarned though, chasing distance, and long range range precision shooting in general is very easy to chase the rabbit down the hole and get addicted! Nothing like 1+ second flight times that allow a guy to come out of his scope, and get back in it in time to see the splash down range.

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    Member Longbow6360's Avatar
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    I calculate these things all the time. Give me the info for your velocity, your bullet (I'll look up the g7 BC), your scope/reticle, sight-in distance and how high your scope is above the bore. I have to go install a scope on a 300WSM and when I'm done I'll figure it out for you.

  6. #6

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    So........then the next question is: Is the rotation of the earth a consistent speed.......???? And at what range do shooters start to factor this rotation into bullet flight relative to the target.........???

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    Quote Originally Posted by AGL4now View Post
    So........then the next question is: Is the rotation of the earth a consistent speed.......???? And at what range do shooters start to factor this rotation into bullet flight relative to the target.........???

    Don't forget moon phases too.
    When seconds count, the cops are just minutes away.
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    Quote Originally Posted by AGL4now View Post
    So........then the next question is: Is the rotation of the earth a consistent speed.......???? And at what range do shooters start to factor this rotation into bullet flight relative to the target.........???
    Ha, ha, actually it is. At the equator it's 1000+ mph. If you're shooting north to south you might want to hold into the earth's rotation.

  9. #9

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    I understand that the rotation of the earth and "Time in Flight" does factor into long shots. However; I don't know what if any effect the moon has.


    Quote Originally Posted by Music Man View Post
    Don't forget moon phases too.

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    Quote Originally Posted by AGL4now View Post
    I understand that the rotation of the earth and "Time in Flight" does factor into long shots. However; I don't know what if any effect the moon has.
    The moon has zero effect on your shots. That gentleman was just pulling your leg a bit. As to the coreolis (sp) effect, you will not notice it, or it will have minimal effect at shots under a mile. Even at that it is most realized at 90degrees from the equator i.e. Straight north or south shots.

    You'd be well advised to focus your learning curve on reading the wind and up and downward angles and the effects it has on your dope.


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  11. #11

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    This is NOT something that I give a rats butt about. But in my novel I have three two man teams on "Overwatch" on each side of Turnagain Pass area. Each two man team is on Overwatch for two hours and off for four hours. This is one of the subjects that get discussed by "ACT-3" (each team is named after a local creek, ACT-3 is Alder Creek Team 3). They have to hold both, the old and new Canyon Creek bridges, till....................(To be continued)

    Quote Originally Posted by orion94us View Post
    ..........You'd be well advised to focus your learning curve on reading the wind and up and downward angles and the effects it has on your dope.
    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by AGL4now View Post
    So........then the next question is: Is the rotation of the earth a consistent speed.......???? And at what range do shooters start to factor this rotation into bullet flight relative to the target.........???
    If you really want to understand this from a shooters point of view; take a look at this: http://bulletin.accurateshooter.com/...ect-explained/
    Then again if you want to learn about it, you can look at it from my point of view and read FM 6-40
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    Craig

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    Member orion94us's Avatar
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    Quote Originally Posted by AGL4now View Post
    This is NOT something that I give a rats butt about. But in my novel I have three two man teams on "Overwatch" on each side of Turnagain Pass area. Each two man team is on Overwatch for two hours and off for four hours. This is one of the subjects that get discussed by "ACT-3" (each team is named after a local creek, ACT-3 is Alder Creek Team 3). They have to hold both, the old and new Canyon Creek bridges, till....................(To be continued)
    Aaaannd at that I'm out. I apologize for my misconception as I thought you were a shooter wanting to get into long range shooting or trying to learn more so as to make educated decisions on how to set up your rifle or where to focus your training. Hope your novel comes out great have a nice day.


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  14. #14

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    Sorry.....I did not intend to mislead anyone. I do run drills several times a week, (I ran three drills today) on my private range, but I max-out at 300 meters.


    Quote Originally Posted by orion94us View Post
    Aaaannd at that I'm out. I apologize for my misconception as I thought you were a shooter wanting to get into long range shooting or trying to learn more so as to make educated decisions on how to set up your rifle or where to focus your training. Hope your novel comes out great have a nice day.


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    Member Longbow6360's Avatar
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    Oops, I also must have misunderstood your post. Sorry.
    However, I would be interested in your novel. Sounds like a pretty cool idea for a story. I've had several people on this site recommend books to read. All have turned out to be excellent reads.
    Chuck.

  16. #16

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    Well, I still have a 25 MOA base on one of my M-70, but I have not really done much work with it. I did have a M-70 in .300 RUM that I had planned to to set-up for long range.

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    Member Nanook's Avatar
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    Just to be sure that we are all singing off the same sheet of music; according to the NRA, mid range is 300-600 yards, Long range is 800-1000 yards and ELR is beyond 1000 yards. Yes! the target shooting community in the English speaking countries defines range in yards. Meters are used when NATO becomes involved. or-or, if you gotta sound Tacticool!

  18. #18

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    At 69 y/o I am NOT into Tacticool. Side Note: I know a guy named Craig P. that builds quality long shooters........would you be him......???

    Quote Originally Posted by Nanook View Post
    Meters are used when NATO becomes involved. or-or, if you gotta sound Tacticool!

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    Member Nanook's Avatar
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    That be me. I turned 69 about 6 years ago.

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    Glad your still alive Craig.

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