Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Hunting > Long Range Hunting & Shooting

Long Range Hunting & Shooting Nightforce Optics


Reply

Wind shooting

 
LinkBack Thread Tools Display Modes
  #8  
Old 02-17-2004, 09:32 AM
Silver Member
 
Join Date: Dec 2003
Location: Stamford NY
Posts: 160
Re: Wind shooting

Dave,

That answer makes alot of sense, but im going to also ask would that only work if the bullet was moving at a constant speed, by the time the bullet gets out there its moveing alot slower and the wind has more time to act on it causing more than 1/2moa drift [img]images/icons/confused.gif[/img].
Reply With Quote
  #9  
Old 02-17-2004, 10:47 AM
JBM JBM is offline
Silver Member
 
Join Date: Jan 2004
Location: New Mexico
Posts: 113
Re: Wind shooting

I don't really think it has all that much more time. There are really two things we're talking about here. First, how much angular deflection you get for a given wind and second, how much that angular deflection moves the bullet. Of course if the deflection is farther down range then it causes less wind drift on the target.

I've never been good at remembering numbers so I ran a few of test cases with a point mass program. They are all 10 mile/hour winds. One is a constant wind from 0 to 1000 yards. The next is from 0 to 100 yards and the third is 500 to 600 yards. All have trajectories to 1000 yards.

Here are the URLs:

wind_10_000_1000.txt
wind_10_000_100.txt
wind_10_500_600.txt

Please note the version number of the program running these (<1) so I'm covering my butt.
__________________
JBM Small Arms Ballistics -- http://www.eskimo.com/~jbm
Reply With Quote
  #10  
Old 02-17-2004, 10:59 AM
JBM JBM is offline
Silver Member
 
Join Date: Jan 2004
Location: New Mexico
Posts: 113
Re: Wind shooting

Also I might add that the deflection at the near range (0 to 100 yards) is about .6 inches and at the 500-600 yard range is about an inch. The difference at 1000 yards ends up being a few inches.

Here's another file with the same 10 mile an hour wind from 900 to 1000 yards.

wind_10_900_1000.txt

Note that the deflection is at little more than twice (1.5") about the 0 to 100 yard wind deflection which is what we would expect since the velocity has fallen to less than half the muzzle velocity. (See the standard wind formula and you'll see that it has the velocity in the denominator...)
__________________
JBM Small Arms Ballistics -- http://www.eskimo.com/~jbm
Reply With Quote
  #11  
Old 02-17-2004, 11:12 AM
Platinum Member
 
Join Date: May 2001
Posts: 2,369
Re: Wind shooting

JBM

Thanks for the reply and most welcome info. This is the first time I've seen this type of output from a ballistics program and I'm excited.

Would you be so kind as to rerun this same info with a muzzle velocity of 2660, BC of .470 @ STP. This I believe is about the standard for the "older" standard military "sniper" rounds data that I've somewhat committed to memory.

Thanks.
Reply With Quote
  #12  
Old 02-17-2004, 11:22 AM
Silver Member
 
Join Date: Dec 2003
Location: Stamford NY
Posts: 160
Re: Wind shooting

JBM,

Thanks for posting that, I looks that wind effect the bullet at the same angle thru out its trajectory, it just depends on where the wind start/stops inorder to determine the amount of drift.

Thanks,
Brian
Reply With Quote
  #13  
Old 02-17-2004, 11:39 AM
Platinum Member
 
Join Date: May 2001
Posts: 2,369
Re: Wind shooting

Brian

That's what I read from JBM's posts and have understood to some degree. Constant wind over the entire flight is additive to previous wind caused deflection. Singlular (short wind period(s)) are more difficult but there is no more cumulative induced deflection after the initial deflection, just continuation of the angular error. Confused myself on that one!

[ 02-17-2004: Message edited by: Dave King ]
Reply With Quote
  #14  
Old 02-17-2004, 01:00 PM
JBM JBM is offline
Silver Member
 
Join Date: Jan 2004
Location: New Mexico
Posts: 113
Re: Wind shooting

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Singlular (short wind period(s)) are more difficult but there is no more cumulative induced deflection after the initial deflection<HR></BLOCKQUOTE>

I think it's interesting to see the angular change stop after a while. Take a look at the file test_470_10_000_100.txt (link above) and you can see that the bullet is accelerated off course, and then the velocity in the cross wind direction goes to a constant after about 600 yards and the windage MOA stays at 1.4 MOA all the way to 1000 yards (constant anglular deflection).

[ 02-17-2004: Message edited by: JBM ]
__________________
JBM Small Arms Ballistics -- http://www.eskimo.com/~jbm
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Wind shooting
Thread Thread Starter Forum Replies Last Post
LR Shooting and Wind Reading Clinic / Matches - Missoula, MT 9/23-9/25 jameydan Long Range Competition 4 11-03-2011 04:05 PM
starter budget cheap wind meter...that still reads wind!?! hmbleservant Long Range Hunting & Shooting 3 06-25-2011 10:43 PM
More shooting with the APS 7mm Dakota XP (high wind Alert) Ernie General Discussion 2 09-16-2006 04:49 AM
Good Fun - shooting in a gale wind Ian M General Discussion 1 08-13-2005 08:09 PM
Formula for shooting in a cross wind.. kc The Basics, Starting Out 2 01-20-2003 08:47 PM


All times are GMT -5. The time now is 03:03 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC