How to measure on MOA picatinny rail?

Discussion in 'Long Range Hunting & Shooting' started by buglum, Mar 3, 2012.

  1. buglum

    buglum Member

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    I just bought a Savage FCP HS precision Lapua. I have read people commenting on differences in what rails came on their rifles. Im relatively new to this and do not know how to determine if the factory rail is 0MOA or 20 MOA. Can anyone explain how to tell the difference?

    Can I just measure the stock end and barrel end of the rail, and if the stock end is higher that means its probably a 20 MOA?

    Their was too much technical talk when I used the search methods. Thanks!
     
  2. emn83

    emn83 Well-Known Member

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    simply put, a 20MOA base is slanted, like you said, the rear end of the base will be higher than the fore end.
     

  3. buglum

    buglum Member

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    How obvious is the height difference between the ends. Should it be obvious to the naked eye? When I hold it up the rail looks parallel to the action but I'm not sure how small of difference I'm looking for
     
  4. emn83

    emn83 Well-Known Member

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    it should say 20MOA on it if it's a 20m MOA base. I'm pretty sure if it's a stock base on a Savage it will be a 0MOA base
     
  5. kcebcj

    kcebcj Well-Known Member

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    If the scope is mounted rotate the turret or adjuster in the down direction till it bottoms out and keep tract of the distance. If you know the total adjustment range of the scope that will kinda tell you how far off center your cross hair is. This won't be exact but should tell you roughly if it's a zero, ten or twenty. If it's a zero the amount of adjustment up and down should be about the same within reason. All scopes are different but this should give you a idea.

    I would think the paper work that came with the rifle would state the amount especially if it was factory installed. It might be marked.
     
  6. Sully2

    Sully2 Well-Known Member

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    If its totally a factory setup.....just call Savage and ask!lightbulb
     
  7. HoytFlinger

    HoytFlinger Well-Known Member

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    The best I can measure my Badger 20 moa rail is .455 rear and .400 front (height). It may be off a little as I measured it mounted to the action.
     
  8. SidecarFlip

    SidecarFlip Well-Known Member

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    We discussed this before and I have the same rifle. It's a 20 MOA Picatinny base. It's easy to tell, Just remove it and mike the back end (or use calipers) and then the front. The brake and the rail are both made by the same company BTW.

    If you don't want to remove it (though I suggest you do because my hold down screws weren't evenly torqued or loctited with blue threadlocker), just lay a good machinist scale against the back and note the dimension and then the front and note the dimension. Of course your Wal-Mart plastic ruler won't suffice, you'll need a real ruler graduated in 64ths of an inch........

    Or you can call Savage, give them the model and serial number and they'll tell you.... what I just told you...... 20 MOA.

    It's nice it only fits on one way. Removes the chance for stupidity.:)
     
  9. jsthntn247

    jsthntn247 Well-Known Member

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    If you are trying to determine ring height, you better know your base height. I used the formula base height + ring height - scope outside diameter times .5. I have a night force 20 moa rail that measure .32 high. Based on that formula I knew I needed bases 1.15" high. I talked to a ring manufacturer that assured me their .97 rings were high enough so I ordered them even though my calculations said they would only give me .001 clearance.
    Got them in yesterday and guess what... They were not high enough, had exactly .001 clearance at most. now I just hope I can swap them out. If you don't know, take them off and measure them and save yourself the head ache.
     
  10. RioHondoHank

    RioHondoHank Well-Known Member

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    Since 1 moa is approximately 1 inch at at 100 yds, you can divide the length of your base in inches by 3600 (inches in 100 yds) to get a figure for thickness difference per moa for each end of you base. For instance if your base is 6 inches long it would be .00166 inches, so 20 moa 6 inch long base would be .033 inches thicker at the back than the front.