The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools
Old October 8, 2012, 05:03 PM   #1
TheNatureBoy
Senior Member
 
Join Date: September 6, 2007
Posts: 1,177
Comparing advertised B.C. w/Independent Measurements

Some of you may be aware of this report already but its a good read. This was a independent study performed by the U.S. Air Force Academy that "addresses the question of ballistic coefficient accuracy. This project compares ballistic coefficients advertised by four well known bullet companies (Hornady, Nosler, Sierra, and Barnes) with those measured by an independent source (Bryan Litz). B.C.s were determined using calculations at the JBM Ballistics web site. Many published ballistic coefficients are significantly different from independent measurements."
See the report here:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA554683

Last edited by Brian Pfleuger; October 9, 2012 at 11:37 AM. Reason: Makes more sense to link to the report....
TheNatureBoy is offline  
Old October 8, 2012, 09:09 PM   #2
jepp2
Senior Member
 
Join Date: December 24, 2008
Location: Loveland, CO
Posts: 1,311
Good information, I hadn't see the report. Most BC's were found to be within 5% of the published values. I know Sierra lists multiple BC's for each bullet based on velocity. I wonder how they selected the BC to use for their comparison?

Bullet Name FMJBT
Diameter inches .224
Weight grains 55
Sectional Density .157
Ballistic Coefficients
.272 @ 3000 fps and above
.245 between 3000 and 2400 fps
.235 @ 2400 fps and below
jepp2 is offline  
Old October 9, 2012, 11:03 AM   #3
TheNatureBoy
Senior Member
 
Join Date: September 6, 2007
Posts: 1,177
Not at all surprised that bullet makers would fudge the numbers a bit because its all about selling product. I don't think its necessary because most hunters don't reload and don't care, and target shooters/reloaders will select the bullet with the highest b.c. value anyway.
TheNatureBoy is offline  
Old October 9, 2012, 06:31 PM   #4
wncchester
Senior Member
 
Join Date: December 1, 2002
Posts: 2,832
Calculating BCs from form factors is pointless; just shoot the things, get muzzle velocity and downrange velocity, then work from that.
wncchester is offline  
Old October 10, 2012, 07:35 AM   #5
30Cal
Senior Member
 
Join Date: December 3, 2002
Posts: 1,095
I think it's laughable that BC's are published to 3 digits.
30Cal is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:50 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.07275 seconds with 9 queries