Consistantly 1 moa off

Discussion in 'Long Range Hunting & Shooting' started by tslesquire, Sep 26, 2012.

  1. tslesquire

    tslesquire Member

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    Ive been using both Strelok and Shooter apps to calculate ballistics for my 300 RUM. Other than making an error when zeroing my turret (which I will be checking this weekend) Does anyone have any ideas of why I would be off by 1 moa? I have shot various ranges out to 840 and every time i have to subtract 1 moa from what the calculator gives me. If it helps, i am using 215 berger hybrids, 89.5 g h100, 3.79 c.o.l., leupold mk4 er/t, 20 moa base. Any help is appreciated
     
  2. JackinSD

    JackinSD Well-Known Member

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    Last edited: Sep 26, 2012

  3. BEEMAN

    BEEMAN Well-Known Member

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    Muzzle velocity may be off and need to be trued as stated earlier. I will be going through the same with my my 300 RUM next week. Just settled on a load of 91 gr H1000, Rem brass, Fed 215 Match primers, COAL 3.843". Want to shoot some drops and get a custom turret ordered but I am running out of time. What is your velocity? I am getting 2988 fps at 1000ft elevation over a chronograph but in another thread guys think it should going over 3000 fps. Also only 6 fps ES.
     
  4. Scot E

    Scot E Well-Known Member

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    could be a few things or a combination of many. Make sure you check your turrets to be sure you know how much they move per click. It sounds like that could be at least part of your problem. Many scopes turrets, including high quality ones, don't match up when you check their actual adjustments to what they list.

    Scot E.
     
  5. tslesquire

    tslesquire Member

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    I am getting 3050 fps at the same elevation
     
  6. jmason

    jmason Well-Known Member

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    Ding, ding, ding!!
     
  7. 1SevenZero

    1SevenZero Well-Known Member

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    here are a couple of things to check.

    Make sure the BC you entered is correct for the profile you selected. (IE. G7 or G1). Odds are if it is a big number like .475 its a G1 BC, and if it is a smaller number like .288 that would be your G1 BC. Your bullet will have both BC numbers, but typically companies advertise the G1 because it looks more impressive.

    Second go online and find an independent BC study of your bullet. I reload Nosler Accubonds and learned they over estimated their BC by around 4%. Doesn't seem like much, but I was experiencing the same thing you were and after making the above changes the ballistic program I was using was spot on.

    Last use your programs verification feature if it has one.
     
  8. reelamin

    reelamin Well-Known Member

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    I found this on a search as I am having the same issue. I just went and started verifying my data at shorter ranges. I started with 600yds tonight, and the G7 data was a full five clicks or 1.25" too high.

    I checked and re-checked the data and it continued to come up the same. Maybe someone could check it again for me?

    300RUM, 190VLD Hunt @ 3360fps (pro chrono and Pact), 1000', 75 degrees, 20 percent humidity, Scope Height 1.75".

    Leupold 6.5x20 with target turrets. A full turn results in 16" of elevation change, and it tracks perfectly in all directions.

    G7 says I should be 8.2" high or 33 clicks up at 100yds. In reality it was 28 clicks up...and all three rounds well inside 8" target.


    700 yards tomorrow night hopefully.
     
  9. reelamin

    reelamin Well-Known Member

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    FIGURED MINE OUT! THE MATH WAS CORRECT! 2+2 IS 4 NO MATTER HOW MUCH YOU DON'T BELIEVE IT OR THE POLITICIANS TRY TO TELL YOU OTHERWISE!

    My problem was my Leica 1200 was way off. I never measured previously just started shooting at what it said across open fields. The 1200 was two years ago and it has always been dead on since I bought it years ago. Something happened big time this last year or so.

    I took out my new 1600-B today(Internal ballistics suck) and was immediatly getting different readings. Put a new battery in the 1200...and was still getting different readings. So I measured (roller wheel) 100yds on the road...1200 was giving readings of -25-35 yards at 100. 1600 was right on. So then I measured every 100yds and marked it with the wheel and 1600.

    The G7, Shooter, and Pact program were all very close to reality. At 5, 6, 700 my combo is only off 2-3 clicks at 100yds. Every one of the distances would have been close enough to kill, but it took a couple clicks to fine tune it dead nuts.

    LOL...my previous 1000 yard shooting was actually on at about 800. Guess I was not doing as well as I thought.

    Trust the program...it uses math...and math is always correct as long as the correct process is used.