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20MOA scoe base on my 7mm mag

Discussion in 'Rifle Discussion' started by mjbskwim, Oct 30, 2015.

  1. mjbskwim

    mjbskwim Salmon,Idaho Well-Known Member

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    I ordered a 20moa 1 piece scope base for my 7mm. I was done with deer so I decided to put that nice VX3 on my 7mm so I could go wring it out.
    I did as usual and set the target at 25 yards to see where it was shooting. And I had got it OK.I ranged a sign at 230yds to center it at home
    After getting it close at 25,everything in a decent little group I went to 100.Couldn't see where it hit.So I up a second target below,I figured it was shooting a little high.
    But a foot? Funny part was I had put stickers over the shots from 25 yards. And even though I was shooting at 100 yards and at the lower target,I put a shot thru each patch!
    So the question is ,why would there be that much difference at 100 yards?
    Most times i have sighted guns in this way the 100 yard shot is at least on the 12"X12" target.
    Is it the 20MOA base that is making the difference or is the 7mm trajectory that different?

    Thanks in advance
  2. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    If your rifle and scope are sighted in and dead-on at 100 yards,
    A zero moa scope base will cause the bullet to strike the x ring at 100 yards
    A 20 moa scope base will cause the bullet to strike 20 inches high at 100 yards
    I went to Gundata.org for a Federal Sierra 150 grain Game King
    7mm Rem Mag Trajectory calculated.JPG

    If your rifle shoots this bullet at a muzzle velocity of 3110 feet per second, and
    you are 12 inches high at 100 yards, you wll be dead-on at 310 yards
    you are 20 inches high at 100 yards, you will be dead-on at 380 yards
    P7id10T and mjbskwim like this.
  3. Dyjital

    Dyjital Albany, Ore Flavorite Member

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    Math. Gotta love it!
  4. mjbskwim

    mjbskwim Salmon,Idaho Well-Known Member

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    I'll mount it back up (I was thinking of taking it off and putting a regular base on) and keep it centered for 100 yards to find the correct ammo. then I'll stretch it out till I have the scope fairly close to to medium values on the turret to see what distance I want to sight it in at.
  5. coyote223

    coyote223 NW Oregon Stamp Collector,,,

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    Go out in shorter jumps, 50yds, 75 yds. I put a 20 moa on my Remmy 7mm with Leupold VXIII, no probs getting it sighted in. Shouldn't be an issue,,,
    mjbskwim likes this.