HuntingNut
HuntingNut
   Login or Register
HomeCommunity ForumsPhoto AlbumsRegister
     
 

User Info

Welcome Anonymous


Membership:
Latest: trice001
New Today: 0
New Yesterday: 1
Overall: 12519

People Online:
Members: 0
Visitors: 42
BOT: 4
Total: 46
Who Is Where:
 Visitors:
01: Forums
02: Forums
03: Forums
04: Forums
05: Forums
06: Forums
07: Forums
08: Forums
09: Forums
10: Forums
11: Photo Albums
12: Forums
13: Forums
14: Forums
15: Forums
16: Forums
17: Forums
18: Your Account
19: Forums
20: Forums
21: Forums
22: Forums
23: Forums
24: Your Account
25: Forums
26: Forums
27: Forums
28: Forums
29: Forums
30: Forums
31: Forums
32: Forums
33: Forums
34: Forums
35: Forums
36: Forums
37: Forums
38: Forums
39: Forums
40: Forums
41: Home
42: Forums
  BOT:
01: Forums
02: Home
03: Forums
04: Home

Staff Online:

No staff members are online!
 

Coppermine Stats
Photo Albums
 Albums: 304
 Pictures: 2343
  · Views: 313856
  · Votes: 1302
  · Comments: 85
 

Support our Advertisers

Ballistic Coefficient (BC) Testing and Analysis
Discussions related to Guns and Firearms
Go to page Previous  1, 2
View previous topic :: View next topic  
Author Message
DallanC
Site Admin
Site Admin


Joined: Jan 18, 2005
Posts: 3164
Location: Utah

PostPosted: Fri Jun 16, 2017 9:42 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

I find it a little wierd on a website created for a specific ballistics software, to see links to competitors software. Ah well I guess.

Anyway Sierra feels BC should be bracketed depending on velocity. For a specific bullet there are usually 3 BC values depending on velocity. I've had more than a few requests to update PointBlank to support this... but as they are the only MFG to my knowledge using multiple BCs, I've never found it worth the effort.

Also, why does no-one talk about bullet deformation due to different rifling configurations? A BC is only good for a specific barrel. Riflings cut deeper or shallower will deform a bullet in different ways, affecting the overall shape of the bullet, which in turn affects BC.

Ever looked at the bore of a Newton rifle?


-DallanC
Back to top
View user's profile Photo Gallery
PaulS
Super Member
Super Member


Joined: Feb 18, 2006
Posts: 3418
Location: South-Eastern Washington - the State

PostPosted: Sat Jun 17, 2017 2:48 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

The published ballistic coefficients are corrected for altitude, barometric pressure and zero humidity. If they weren't then the BC would be meaningless. Using a G1 BC in Point Blank and other good software adjust the "working BC" for the altitude and other parameters that exist when and where you shoot.
You got a BC calculated at 1800 feet with 29.40 pressure and 45% humidity then it would have to be lowered at sea level at 29.91 pressure and 60% humidity to match the trajectory there. If I used your calculated BC (while assuming it was corrected to sea level standard atmosphere using Point Blank at 2000 feet above sea level and 80F with 10% humidity the software would come up with nonsense because the software would reduce the friction for my 2000 feet and higher temperature while increasing the drag for the low humidity.
Dallan shows reason for more deviations in BC and how about the tipped bullets that overheat and melt away in flight? That will give a lower BC than if you fired the same bullet at a lower velocity even under the same environmental conditions.
The BC provided by a manufacturer has to be corrected to the standard atmospheric conditions to be meaningful when used in software under different conditions or you get garbage out. The software you use might make those conversions but it might not too. Before using measured or calculated BC for reference there must be a reference point. The standard atmosphere is the "normal" reference point for BCs.

_________________
Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads
Back to top
View user's profile Send e-mail
Elvis
Super Member
Super Member


Joined: Jul 27, 2008
Posts: 7066
Location: south island New Zealand

PostPosted: Sat Jun 17, 2017 3:18 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

shooting a 130-180grn projectile at 2900-3000fps at 0-350 yards
you sight in to be 3" high at 100 yards and forget all the other B.S. and just go shoot you some deer.
yip the flat or round nose jobbie wont hold up as good as the sleak splitzer with superduper arodynanically designed nose cone and moly coating to make it slipperyer than a whores drawers
BUT crunch the numbers on my 170grn RNFB speers going say 2800fps from my .270 and you will see what I mean..at the sub 300 yard range where lets face it 90% of animals are shot,the difference is sweet stuff all.

_________________
You shot it You pluck it !
Them who eats the most duck eats the most feathers!
Back to top
View user's profile
slimjim
Super Member
Super Member


Joined: May 16, 2009
Posts: 7171
Location: Fort Worth TX

PostPosted: Sat Jun 17, 2017 3:43 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

DallanC wrote:
I find it a little wierd on a website created for a specific ballistics software, to see links to competitors software.

Dallan, my apologies. The computer I use cannot have any software apps loaded on it that are not approved. Thus I use on-line ballistic calculators. If you have any suggestions to reference Pointblank, I'm open. I just doing have any experience with it.

_________________
"To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt

"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein
Back to top
View user's profile
slimjim
Super Member
Super Member


Joined: May 16, 2009
Posts: 7171
Location: Fort Worth TX

PostPosted: Sat Jun 17, 2017 3:47 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

PaulS wrote:
The published ballistic coefficients are corrected for altitude, barometric pressure and zero humidity. If they weren't then the BC would be meaningless.

PaulS, I thought I explained that the BC derived from this testing were corrected for altitude, barometric pressure and humidity. One also has to correct for temperature and winds. You are correct, in the situation where I didn't have accurate altitude, barometric pressure, and humidity, the BCs were meaningless.

_________________
"To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt

"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein
Back to top
View user's profile
slimjim
Super Member
Super Member


Joined: May 16, 2009
Posts: 7171
Location: Fort Worth TX

PostPosted: Sun Jun 18, 2017 7:32 am    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

Elvis wrote:
BUT crunch the numbers on my 170grn RNFB speers going say 2800fps from my .270

Elvis, the 150s I shoot out of my .270 are pretty stout at 2800 fps. What powder are you using to get a 170gr to 2800 fps?

_________________
"To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt

"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein
Back to top
View user's profile
Elvis
Super Member
Super Member


Joined: Jul 27, 2008
Posts: 7066
Location: south island New Zealand

PostPosted: Sun Jun 18, 2017 10:51 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

pushing them with ar3312 and a couple of grains over book max 54grns..... as for how fast they going........ dont own a chrony.

_________________
You shot it You pluck it !
Them who eats the most duck eats the most feathers!
Back to top
View user's profile
Elvis
Super Member
Super Member


Joined: Jul 27, 2008
Posts: 7066
Location: south island New Zealand

PostPosted: Sun Jun 18, 2017 10:56 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

nick harvey has in text 56grns of 4831 for 2800fps...he had longer barrel and those early loads of his are hot.

_________________
You shot it You pluck it !
Them who eats the most duck eats the most feathers!
Back to top
View user's profile
PaulS
Super Member
Super Member


Joined: Feb 18, 2006
Posts: 3418
Location: South-Eastern Washington - the State

PostPosted: Tue Jun 20, 2017 8:00 pm    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

Slimjim,
You may have said it and I just missed it or forgot seeing it. Either way the BC has meaning under those conditions for you. If the software does it all and gives you the corrected number then it is golden!

_________________
Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads
Back to top
View user's profile Send e-mail
slimjim
Super Member
Super Member


Joined: May 16, 2009
Posts: 7171
Location: Fort Worth TX

PostPosted: Wed Jun 21, 2017 5:33 am    Post subject: Re: Ballistic Coefficient (BC) Testing and Analysis Reply with quote

PaulS, with my test results consistent with Applied Ballistic and repeatable, it gives me confidence the process is working.

_________________
"To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt

"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein
Back to top
View user's profile
Display posts from previous:   
Post new topic   Reply to topic   Printer Friendly Page    Forum Index » Gun & Firearm Discussions
Page 2 of 2
All times are GMT - 7 Hours
Go to page Previous  1, 2



Jump to:  


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Advertisements
 


Valid CSS! Valid HTML 4.01!
Click to check if this page is realy HTML 4.01 compliant for speed :)

All logos and trademarks in this site are property of HuntingNut.com.
The comments are property of their posters, all the rest © 2011 by HuntingNut.com
Interactive software released under GNU GPL, Code Credits, Privacy Policy

.: Upgraded to DragonFly 9.2 by Dizfunkshunal :.