changing altitude and temp now what

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by tjonh2001, Mar 3, 2008.

  1. tjonh2001

    tjonh2001 Well-Known Member

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    I shoot long range 20-100 rounds per week.especially since F-class is comming up.here is my question.I hunt at 2750 altitude usually temp around 30 degrees. So I went out and made drop charts at those ranges by shooting in 50 yard incroment .yes I used exbal to get me close.now that I have my chart set up. Because things change with alt and temp, what am I suposed to use on my up coming elk hunt at 9000 ft. I know that you guys use exbal in a palm. That's what I am thinking of doing but every time that I go out and use exbals on my (lab top)the information is usually off. I am spending to much money for these hunts to miss because my info is wrong. What are you guys doing to get those programs to work to the fullpotential.because I don't have the time to make a new chart for all the differnt alts and temp that I might run into with this rifle...

    Also does anyone have a palm with exbal that they would lik to sell PM me.....
     
    Last edited: Mar 3, 2008
  2. Mikecr

    Mikecr Well-Known Member

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    Competition, and long range hunting, are about a million miles apart huh?

    If your sure of a narrow altitude spread, you could make drop charts within the range. Cards to carry.
    Otherwise it's best to invest in a Krestel so that you can measure local pressure. Get a Leica LRF, and pick up a palm for local use of Exbal. This is a pretty accurate shooting system for reasonable ranges.
    But you have to practice with it, and work out a routine(NOT at set ranges & off a benchrest).
     

  3. tjonh2001

    tjonh2001 Well-Known Member

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    thats the thing i use leica geovids and a kessel. i have done alot of reading here and other sites. i am wondering if you guys find a chart on you exbal that coinsides with your performance and use that as your performance numbers. velocity 3160 and a bc .648 in the mauals. when i put it in my exbal i have to change the bc to .64 fps to make it match my chart. so now when i am at a different altitude i should use those numbers and i can just change temp and pressure and i should hit my targer. is that what you guys are saying
     
  4. MagMan

    MagMan Well-Known Member

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    Last edited: Mar 4, 2008
  5. Buffalobob

    Buffalobob Writers Guild

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    It is usually the case that the BCs that corresponds to your drop data will be lower than the advertised number.

    If your chronograph is accurate then you should always use the BC of 0.64.


    For making a drop chart use 9000 feet and your best guess as to what the temperature will be at shooting time (early morning or late evening).

    If you are serious about not enjoying spending a lot of money for a hunt and then having it go badly (and I know what you mean about that) then you will need an accurate wind meter. You can spend a fair amount of money on a stand alone wind meter such as the bottom of the line Kestrel or you can spend increasing amounts of money to purchase the higher up models which will include a a lot more weather variables. A cheap thermometer hung on a pole at camp will get you pretty close to temperature. A good topo map will get you the altitude. If you use an altitude and temperature correction and a humidity of 50% then you are pretty close. The use of barometric pressure is more accurate and that is for sure, but the difference is very small, so we are talking about a small difference.

    Some of this is just how much money you wish to spend.