Zero in Fl to shoot in Mt

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 1947flaboy, Feb 17, 2014.

  1. 1947flaboy

    1947flaboy New Member

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    I zero in Florida, 90 degrees, near sea level, high humidity, to hunt in Montana, 20 to 40 degrees, 4000 ft altitude, low humidity. Is there some way to adjust my Fl zero to approximate Montana conditions or must I re zero in Montana. A long shot would be 350 yards.
     
  2. NEMTHunter

    NEMTHunter Well-Known Member

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    At what range do you zero your gun at? It will defiantly have less drop up here then you would in Florida. I would say for the first 300 to 400 yards its not a really big deal. But it will make a BIG difference out beyond 500 and up. I would feel you would be safe to zero it @ 100 or 200 yards and just go with that up here. BUT it could not hurt to shoot a couple rounds up here to see how close it will be. My guess is it will still be right on if you zero it @200 yards. maybe .2" high but more then likely it will be spot on.

    Have fun!! Montana is a great state to hunt in!
     

  3. 264WM

    264WM Well-Known Member

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    Use the G7 ballistics calculator above you can put in the conditions where you sighted in your rifle then change the elevation, temperature, wind and pressur re calculate and It will give you the changes.
     
  4. bootsking

    bootsking Active Member

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    My 300WM was zeroed at 200yd in NC at 500 feet. Went to Co mid Sept to hunt, the temperature was about the same, and the POI was about 1.5" higher due to the 6000 ft altitude difference. Fast forward a year; went back around Thanksgiving to the same area and the POI shifted 3" low due to the major temperature drop. Same exact loads, same rifle, same 200 yd zero before the hunt. While the ballistic calcs may handle the altitude and air temp shift ok, I doubt your data regarding velocity change due to temperature will be adequate and will require shooting to insure proper performance.

    Related to that, I always leave my rifle and ammo outside in the truck to stay acclimated to the conditions of the hunt for consistency after zeroing.
     
  5. rick523

    rick523 Well-Known Member

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    There are a lot of things to take into consideration, are you using a ballistic app? How confident are you in your input data? Do all your drops work out to your out put data,(check this by actually shooting for drops). Are you using temp stable powder?

    If the answer to these questions are yes, if you put in all the correct data from your hunting area you should be good to go. But you still may want to take a couple of confidence shoots if you feel the need. I sighted in here in Indiana, 500ft elevation went to Wy. last year made a 803 yd. shot on a muley. One shot one kill and didn't take any sighters, but my confidence was high because I knew all my ducks were in a row.:D
     
  6. 264WM

    264WM Well-Known Member

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    The chart is to get you close it is always smart to take a couple test shots as scopes can get bumped in travel by on of your partners and they may not tell you. The velocity drop in the barrel is not going to be enough to matter.:D
     
  7. BrentM

    BrentM Well-Known Member

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    I agree. We have all of our hunters re-zero due to travel. If a LR hunter showed up we verify zero and 500 for drop especially for guys who don't use temp stable powders. However for 350 or less POI shift due to velocity change should not be an issue.
     
  8. MontanaRifleman

    MontanaRifleman Well-Known Member

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    At 350 yards being a long shot, it won't matter much. Colder temps and higher altitude will also counter each others effects.
     
  9. kiwi3006

    kiwi3006 Well-Known Member

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    If you use the shooter app for your smartphone it allows you to record the conditions when you zeroed, so will make all the adjustments for you.
    But like it has been posted earlier, out to 350 it won't make much difference.
     
  10. BrentM

    BrentM Well-Known Member

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    I use shooter and thought I would run a basic calculation. If I input 27absolute and 22 absolute and leave temp alone the difference at 350 on a 200 yrd zero is .6". Those numbers roughly are the same conditions from FL to MT.
     
  11. FEENIX

    FEENIX Well-Known Member

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    Where in MT are you hunting? There might be a range nearby or on your way to your final hunting area for you to check your zero.

    For as long as Murphy is involved, I personally would shoot it to make sure.