Long Range Hunting Online Magazine


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


Reply

Velocity and Altitude question

 
LinkBack Thread Tools Display Modes
  #1  
Old 03-31-2014, 07:22 PM
Silver Member
 
Join Date: Jul 2012
Location: Shasta County
Posts: 207
Velocity and Altitude question

I live 500' above sea level and hunt at 9000-11500 feet. I know ballistics change with altitude, but I'm wondering if velocity does too. If I recall correctly, if I'm shooting 3280 at 500' elevation, at 11000 or so, the velocity should be higher. I guess the sure way to know is shoot the gun through my chrony at somewhere close to that altitude, but I can't do that until I go back in October.

Or, do I put the parameters into the ballistics calculators and do they do the math for me?
Reply With Quote
  #2  
Old 03-31-2014, 09:18 PM
Silver Member
 
Join Date: Dec 2013
Location: End of the Oregon Trail
Posts: 397
Re: Velocity and Altitude question

Velocity change in the barrel due to elevation is not a factor. A chrony 15 Ft away will probably be well within your ES to and not a factor.

If you use an app like Shooter, it calculates the altitude change for you based on the altitude/temp/pressure where you sighted in at.


It is a very good idea to actually do some practice shots and verify everything at the altitude you will be hunting at anyway IMHO.
Reply With Quote
  #3  
Old 03-31-2014, 11:35 PM
Platinum Member
 
Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,168
Re: Velocity and Altitude question

It's an INTERNAL ballistic factor and wouldn't be accounted for in any EXTERNAL ballistic math.
I know it can affect tune. I don't know about muzzle velocity.
Reply With Quote
  #4  
Old 04-01-2014, 12:28 PM
Silver Member
 
Join Date: Jul 2012
Location: Shasta County
Posts: 207
Re: Velocity and Altitude question

Quote:
Originally Posted by Barrelnut View Post
Velocity change in the barrel due to elevation is not a factor. A chrony 15 Ft away will probably be well within your ES to and not a factor.

If you use an app like Shooter, it calculates the altitude change for you based on the altitude/temp/pressure where you sighted in at.


It is a very good idea to actually do some practice shots and verify everything at the altitude you will be hunting at anyway IMHO.
Thanks for the info.

I always shoot my guns when I arrive and reconfirm zero.

My main reason for asking is I was going to have some turrets made with the drop built in. I'm just trying to make it the best I can before I go ahead with it.
Reply With Quote
  #5  
Old 04-01-2014, 12:30 PM
Silver Member
 
Join Date: Jul 2012
Location: Shasta County
Posts: 207
Re: Velocity and Altitude question

Quote:
Originally Posted by Mikecr View Post
It's an INTERNAL ballistic factor and wouldn't be accounted for in any EXTERNAL ballistic math.
I know it can affect tune. I don't know about muzzle velocity.
I don't understand. Can you explain more?
Reply With Quote
  #6  
Old 04-01-2014, 11:38 PM
Platinum Member
 
Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,168
Re: Velocity and Altitude question

Well, different air density being pushed down a bore could affect the pressure curve a bit, affecting your accuracy. But there are a lot of variables to internal ballistics that could ultimately sum to actual muzzle velocity change -or not.
Reply With Quote
  #7  
Old 04-02-2014, 04:19 AM
Platinum Member
 
Join Date: Jan 2008
Location: Northeast
Posts: 2,233
Re: Velocity and Altitude question

You are not likely to see a big change, if any in muzzle velocity, but it's still advisable to re-zero when changing locations of different altitudes. The difference in the altitude/air density, will produce a lower resistance on the bullet, producing higher retained velocities at longer ranges, thus requiring a lower elevation correction at those longer ranges. a ballistic program , like Shooter will provide the corrections when the air density/altitude info is inputed for the higher elevation.
__________________

"Let us speak courteously, deal fairly, and keep ourselves armed and ready"-T. Roosevelt
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Current Poll
Are you on Facebook?
Yes - 46.51%
1,093 Vote
No - 19.32%
454 Votes
No, but I may join - 1.74%
41 Votes
No way, are you kidding? - 36.21%
851 Votes
Total Votes: 2,350
You may not vote on this poll.

All times are GMT -5. The time now is 04:20 PM.


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