close
Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Rifles, Bullets, Barrels & Ballistics

Rifles, Bullets, Barrels & Ballistics Applied Ballistics

Reply

Altitude and its effects

LinkBack Thread Tools Display Modes
  #1  
Unread 08-21-2008, 02:07 PM
Bronze Member
 
Join Date: Aug 2008
Location: Below the Mason Dixon
Posts: 30
Altitude and its effects

I will be hunting out west for the first time in October. Being from Alabama and having an altitude of around 600ft I am concerned about bullet impact once my rifle is shot in the higher altitude. Of course I will shoot my rifle once I arive in CO but my question is this. If I zero my rifle at 100yds at 600ft altitude what should I expect my bullet to do at 8000 to 10000ft? I know it will climb but how much? Our humidity in Alabama is also high right now it stays at around 70% or higher (90% here latley) so that will have an impact as well. I know from a short range standpoint not much will change but if I were to zero at 200 (like I normaly do) what would I expect as well. I am shoot a 7mm factory loaded Fed. Prem. with a 160 accubond.

Last edited by thunderchicken; 08-21-2008 at 02:10 PM. Reason: forgot info
Reply With Quote
  •   #2  
    Unread 08-21-2008, 02:30 PM
    Platinum Member
     
    Join Date: Mar 2005
    Location: Utah
    Posts: 1,375
    Re: Altitude and its effects

    I could do it for you, but... If you go to the bullets, barrels, and ballistics section you will find a thread at the top - ballistic programs, web based and downloadable. I like the one with eskimo in it. Click the link, put in your data, hit calculate, and save. Then do it again changing the elevation, humidity, whatever else you think'll change. Now you can answer these questions whenever you want. Take a look. You'll have more questions.
    Reply With Quote

      #3  
    Unread 08-21-2008, 03:01 PM
    Gold Member
     
    Join Date: Jan 2002
    Location: Wenatchee, WA
    Posts: 806
    Re: Altitude and its effects

    Humidity matters so little as to be negligible. Play around with the aforementioned ballistics progams and you'll see what I mean.

    Altitude matters quite a bit, but you might be time/money ahead to get an altimeter/barometer like a Kestrel 4000 (other models work, its just what I happen to have)... what changes is the barometric pressure (gets less with higher altitudes), but it can change in some weird ways due to local conditions, terrain, etc. so it can help to know what it actually *is*, not just what it 'should be' for a given altitude. Of course, then a PDA becomes pretty helpful... and the list goes on ;)

    In general, you're going to start seeing a noticeable decrease in drop out past 400yds. My 1k zero for a .308 Win 155gr VLD @ 2960fps changed from 31 moa @ 800' ASL to 24' moa @ 6600' ASL.

    Monte
    Reply With Quote
      #4  
    Unread 08-21-2008, 05:51 PM
    Gold Member
     
    Join Date: Sep 2003
    Location: Nebraska
    Posts: 810
    Re: Altitude and its effects

    Quote:
    Originally Posted by thunderchicken View Post
    I will be hunting out west for the first time in October. Being from Alabama and having an altitude of around 600ft I am concerned about bullet impact once my rifle is shot in the higher altitude. Of course I will shoot my rifle once I arive in CO but my question is this. If I zero my rifle at 100yds at 600ft altitude what should I expect my bullet to do at 8000 to 10000ft? I know it will climb but how much? Our humidity in Alabama is also high right now it stays at around 70% or higher (90% here latley) so that will have an impact as well. I know from a short range standpoint not much will change but if I were to zero at 200 (like I normaly do) what would I expect as well. I am shoot a 7mm factory loaded Fed. Prem. with a 160 accubond.
    You better have a good balistic program like Exbal to reference. I sighted in my rifle here at 1400' and took it to 6000 and it still was dead on at 100yds, from there you need a program that will calculate the elevation changes. The Eskimo program works well for a general drop chart, but hard to input changes if its not with you. My rifle has a drop of 17 moa @ 1000yds where i live in Neb. The same loads in Wyo at 6000' changed to 15.5 moa, 1000yds. I made drop charts before i left home and found they were close, but not close enough when your talking long ranges.

    There is no substitute for real testing. I have found Exbal to be very acurate as long as you know all the weather perameters.

    Dave
    Reply With Quote
      #5  
    Unread 08-21-2008, 06:33 PM
    Silver Member
     
    Join Date: Jan 2007
    Posts: 139
    Re: Altitude and its effects

    There is a sticky in bullets, barrels, ballistics about this and it's good information.

    The way I understand it is that you want humidity and absolute pressure ( not corrected pressure). You enter an 0 for the altitiude value. It appears that more than anything drag is the real issue.

    Anyway this is what I walked away from after reading that post.

    As said, you should be throwing a few bullets at you designated altitude to see whats going on . After all the proof is in the puddin.
    Reply With Quote
      #6  
    Unread 08-21-2008, 07:31 PM
    Platinum Member
     
    Join Date: Jan 2008
    Location: West Central Idaho
    Posts: 1,218
    Re: Altitude and its effects

    Quote:
    Originally Posted by thunderchicken View Post
    I know from a short range standpoint not much will change but if I were to zero at 200 (like I normaly do) what would I expect as well. I am shoot a 7mm factory loaded Fed. Prem. with a 160 accubond.
    Just ran your load in Exbal and here is what comes up.At 200 yards the drop from the bore is 7.8 inches at sea level. At 8000 ft elevation the drop from the bore is 7.6 inches. There is .2 of an inch difference. In my opinion not enough to give a second thought for regular hunting out to 400 yards or so. If you shoot beyond that I would resight the rifle at alitude and have a drop chart made for the alitude that your hunting at. If nothing else the darn gun will shoot better the higher you get. Have fun.
    __________________
    Jim



    There is something about the outside of a horse that is good for the inside of a man. Sir Winston Churchill.

    Everything that is really great and inspiring is created by the individual who can labor in freedom. Einstein
    Reply With Quote
      #7  
    Unread 08-21-2008, 08:53 PM
    Gold Member
     
    Join Date: Jan 2006
    Location: Nebraska
    Posts: 507
    Re: Altitude and its effects

    Quote:
    Originally Posted by Black Diamond 408 View Post
    My rifle has a drop of 17 moa @ 1000yds where i live in Neb. The same loads in Wyo at 6000' changed to 15.5 moa, 1000yds.
    Dave
    That's almost like cheating

    You must be talking about the .338 Cheytac.

    James
    Reply With Quote
    Reply

    Bookmarks

    Thread Tools
    Display Modes


    Similar Threads for: Altitude and its effects
    Thread Thread Starter Forum Replies Last Post
    density altitude trueblue Long Range Hunting & Shooting 5 05-10-2013 06:35 AM
    effects of altitude on loads djtjr Long Range Hunting & Shooting 5 10-21-2010 10:05 AM
    temp and altitude? outdooraddict Long Range Hunting & Shooting 1 05-09-2008 05:19 PM
    altitude/pressure Dave Squires Rifles, Bullets, Barrels & Ballistics 1 07-06-2005 09:16 AM
    Altitude & Temperature Effects on a Bullet? 147 Grain Long Range Hunting & Shooting 19 03-10-2005 04:14 PM


    All times are GMT -5. The time now is 05:57 PM.


    Powered by vBulletin ©2000 - 2016, Jelsoft Enterprises Ltd.
    Content Management Powered by vBadvanced CMPS
    All content ©2010-2015 Long Range Hunting, LLC