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

B.C. Variance

 
LinkBack Thread Tools Display Modes
  #1  
Old 08-04-2002, 02:31 PM
Bronze Member
 
Join Date: Jan 2002
Location: Alaska
Posts: 68
B.C. Variance

Could someone tell me what the best way is of allowing for the change in ballistic coefficients at the various velocities over long range for use in computer trajectory calculations?

For example, a given bullet has BC is .450 at 3100fps, .440 at 2400fps, and .372 at 1600fps. What BC value would one use for an accurate trajectory calculation for the entire range of velocities?

Do any of the software programs that are available allow for changing BC values or do they all make the calculations with just one value?

TIA
__________________
Reply With Quote
  #2  
Old 08-04-2002, 03:08 PM
Silver Member
 
Join Date: Feb 2002
Location: Jackson MI
Posts: 247
Re: B.C. Variance

The Sierra Infinity program allows you to enter up to 5 different BC values and the velosity threshold for custom bullets that you set-up in the program. It will also allow you to put in a max range of 8000 yds. That seems a bit long even for the folks around here [img]images/icons/grin.gif[/img]
__________________
"When working with the public, there are two things you need to remember. - 1. The public is a bunch of ignorant morons. - 2. YOU and I are one of them!"
Reply With Quote
  #3  
Old 08-05-2002, 05:43 PM
Bronze Member
 
Join Date: Jan 2002
Location: Alaska
Posts: 68
Re: B.C. Variance

RBrowning, thanks. I just got an email from Robert Treece at Sierra and he confirmed what you said. I have a copy of Infinity ordered.
__________________
Reply With Quote
  #4  
Old 08-06-2002, 02:32 AM
Platinum Member
 
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: B.C. Variance

RB,
Do you mean five different drag curves like the Oehler Ballistic Explorer program does, which has 7, one of which is for rimfire, or is this something else completely?
__________________
Brent Moffitt
Reply With Quote
  #5  
Old 08-06-2002, 10:43 AM
Silver Member
 
Join Date: Feb 2002
Location: Jackson MI
Posts: 247
Re: B.C. Variance

I'm not familiar with the Oheler program so you will have to draw your own comparisons. The Serria Infinity program allows you to define a bullet if there isn't one already in their library. You can put on diameter, weight etc., then you can put in up to 5 BC values and the threshold values for velocity where the BC will change. Generally the lower the velocity the lower the BC. My guess by looking at the values that they post for their own bullets is that you would get a curve if they were plotted. I don't shoot exotic bullets (LRB etc) so I just use what is in the library.

If you do get the software make sure you go to their site and down load the update. It takes a while to download 2.3M but it is worth it - more in the library, more features and runs faster.
__________________
"When working with the public, there are two things you need to remember. - 1. The public is a bunch of ignorant morons. - 2. YOU and I are one of them!"
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: B.C. Variance
Thread Thread Starter Forum Replies Last Post
.22-250 AI Case Variance Doug in Alaska Reloading 8 04-04-2014 04:03 PM
Help with velocity variance Striker77s Reloading 17 01-02-2011 12:12 PM
Headspace Variance statjunk Reloading 13 06-28-2010 07:07 AM
Weight Variance on 200 gr. Accubonds azsugarbear Rifles, Bullets, Barrels & Ballistics 2 11-27-2006 03:19 PM
How much variance should I accept in my brass? JustC Rifles, Bullets, Barrels & Ballistics 10 07-10-2003 11:29 PM


All times are GMT -5. The time now is 08:42 PM.


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