Me + Math = WHAAAAA??? - M14 Forum

M14 Forum


Me + Math = WHAAAAA???

This is a discussion on Me + Math = WHAAAAA??? within the Ammunition forums, part of the M14 M1A Forum category; Can someone help me understand this? Ballistic Coefficient - which is better, or, is it relative to the round? I've got my different MFG hunting ...


Go Back   M14 Forum > M14 M1A Forum > Ammunition

27Thanks
Reply
 
LinkBack Moderator Tools Display Modes

Old March 10th, 2017, 09:05 AM   #1
Platoon Commander
 
Walt Longmire's Avatar
 
Join Date: Nov 2016
Location: CO & WY
Posts: 501
Me + Math = WHAAAAA???

Can someone help me understand this?

Ballistic Coefficient - which is better, or, is it relative to the round?
I've got my different MFG hunting rounds in to test in the M1A for best-in-the-gun accuracy once my optic arrives and I get it zeroed, and one thing the ballistic caclualtor wants to know is ballistic coefficient. So I looked it up on all the rounds and made a spreadsheet to keep handy, wrote it all down, but what I realized is: I have no clue what it means in comparison to one another.

So what I've got is 5 rounds with G1 profiles...
1 round @ 165gr and a 0.496 B.C.
1 round @ 168gr and a 0.470 B.C.
1 round @ 168gr and a 0.503 B.C.
1 round @ 165gr and a 0.447 B.C.
and 1 more round that matched @ 168gr and a 0.470 B.C.

If I understand it right - that would mean the 0.447 round is the best from a perspective of "aerodynamics" of the bullet, correct? It is the round to beat compared to the others, with the 0.503 being the "worst" of the bunch, yeah?

Walt Longmire is offline  
Remove Ads
Old March 10th, 2017, 09:19 AM   #2
Designated Marksman
 
Join Date: Sep 2013
Location: Maryland
Posts: 591
I think you have it backwards, the higher the BC, the more efficient the bullet should be.

Thanks from Warowl
dist1646 is offline  
Old March 10th, 2017, 09:21 AM   #3
Lifer
 
POLACK's Avatar
 
Join Date: Aug 2016
Location: south east Florida
Posts: 2,811
dist yup

POLACK is offline  
 
Old March 10th, 2017, 09:22 AM   #4
Automatic Rifleman
 
Allen Humphrey's Avatar
 
Join Date: Oct 2016
Location: Dry side of Washington
Posts: 130
I probably can't answer all your questions, but I'll give a start.

Ballistic Coefficient (BC hereafter) is not a predictor of accuracy but rather a scale of how aerodynamic it is relative to a standard model. The bigger the number, the more aerodynamic it is. So in your examples the .447 would be akin to a Bristol Blenheim and the .503 would be your P-51 mustang. :)

Accuracy of the bullet is much more about its design and manufacturing (concentric, uniform....) and the contributing factors of the firearm and propellants. There are some very accurate flat base bullets that have low BC.

The confusion is often related to wind drift where higher BC's are less affected by the wind.

Now...if I screwed any of that up, somebody can set me straight.




Thanks from Stg1944, habu1, JEFFJP_N_JJ and 1 others
Allen Humphrey is offline  
Old March 10th, 2017, 09:27 AM   #5
Lifer
 
Wasted ammo's Avatar
 
Join Date: Dec 2016
Location: GA
Posts: 3,674
If you are not shooting high power matches at a 1000 yards you'll most likely never notice the difference. Let the rifle pick the ammo.

Thanks from bfoosh006 and JEFFJP_N_JJ
Wasted ammo is online now  
Old March 10th, 2017, 09:29 AM   #6
Lifer
 
POLACK's Avatar
 
Join Date: Aug 2016
Location: south east Florida
Posts: 2,811
they make online ballistic charts that all you have to to is enter the info.you don't even have to take off your shoes when you get to 10

use a good chronograph,too

Thanks from M14wannabe

Last edited by POLACK; March 10th, 2017 at 10:25 AM.
POLACK is offline  
Old March 10th, 2017, 09:33 AM   #7
Lifer
 
Dougboffl's Avatar
 
Join Date: Nov 2013
Location: Sonshine State, JC
Posts: 2,663
+1 what dist1646 says

Dougboffl is offline  
Old March 10th, 2017, 09:37 AM   #8
Master Gunner
 
Join Date: Feb 2006
Location: Deplorable area of CA
Posts: 963
Fiddling about with the Hornady ballistics calculator, there would appear to be very little difference between bullets with .450 and .500 ballistic coefficient at ranges out to 500 yards.

http://www.hornady.com/ballistics-re...ics-calculator

All the bullets listed in the OP are very, very good. As Wasted Ammo said, you might as well just shoot them all and see which shoots best, ignoring BC.

Tim

Thanks from Wasted ammo
timrb is offline  
Old March 10th, 2017, 09:48 AM   #9
Platoon Commander
 
Walt Longmire's Avatar
 
Join Date: Nov 2016
Location: CO & WY
Posts: 501
Thanks for setting me straight everyone...
These are all hunting rounds - all solid copper, all with some form of polymer tip for better "aerodynamics."

What I find really really interesting in you guys saying the 0.503 is the one to beat - from a "user review" perspective on the various sights I checked before purchase - it has the WORST reviews for consistency. Not bad, but sub 4 out of 5 star rating across multiple sites, multiple reviews.

The 2nd 0.470 has the best overall rating of any round I picked to try, coming in well above 4.5 out of 5 overall average, the 0.447 being the second best. Go figure.

I know user reviews aren't necessarily the most valuable, but they can be helpful.

Obviously it may turn out that the 0.496 is the best feeding, most accurate out of my specific rifle,... I guess we'll have to see soon. But at least now I understand what the heck this whole ballistic coefficient thing means. I thank you all very very much!

Walt Longmire is offline  
Old March 10th, 2017, 09:50 AM   #10
Lifer
 
Wasted ammo's Avatar
 
Join Date: Dec 2016
Location: GA
Posts: 3,674
You got the picture anyway. Bottom line is your rifle will shoot one better than the rest. While my rifle might shoot it the worst, you just don't know until you shoot them.

Wasted ammo is online now  
Old March 10th, 2017, 11:08 AM   #11
Lifer
 
Join Date: Jun 2012
Location: South Charleston, WV
Posts: 2,405
A layman's term for high BC is that a particular bullet "flies better" than another one.

Instructor is online now  
Old March 10th, 2017, 11:24 AM   #12
Platoon Commander
 
Walt Longmire's Avatar
 
Join Date: Nov 2016
Location: CO & WY
Posts: 501
Quote:
Originally Posted by Wasted ammo View Post
You got the picture anyway. Bottom line is your rifle will shoot one better than the rest. While my rifle might shoot it the worst, you just don't know until you shoot them.
That's why I bought 5 different ones that fit my parameters for hunting!

Hopefully I'll see the optic soon (in theory showing up today or Monday), get this sucker out to the range, get it zeroed, with these to test out.

Thanks from Stevie Ray
Walt Longmire is offline  
Old March 10th, 2017, 11:53 AM   #13
Old Salt
 
smoothy8500's Avatar
 
Join Date: Oct 2009
Location: San Clemente, California
Posts: 1,533
How "well" your rifle shoots or groups with a particular bullet is irrelevant to the BC. How well your chosen bullet flies past 300 yds in relation to drop and wind is relevant to the BC.

smoothy8500 is offline  
Old March 10th, 2017, 01:16 PM   #14
Automatic Rifleman
 
Join Date: Mar 2015
Location: Austin Texas
Posts: 155
Quote:
Originally Posted by Walt Longmire View Post
What I find really really interesting in you guys saying the 0.503 is the one to beat - from a "user review" perspective on the various sights I checked before purchase - it has the WORST reviews for consistency.
BC is a measure of how fast the bullet loses velocity as it flies.
BC is also a measure of how much the wind blows the bullet around.

BC is absolutely NO indicator as to how accurate nor precise that bullet is.

MitchAlsup is offline  
Old March 10th, 2017, 02:29 PM   #15
Grunt
 
Join Date: Aug 2011
Location: KS
Posts: 97
Me + Math = WHAAAAA???

For your intended usage, the bullet's Sectional Density is more important than its Ballistic Coefficient. Neither are likely as important as you think.

Enjoy your new research project.

Grizzman is offline  
Reply

  M14 Forum > M14 M1A Forum > Ammunition

Moderator Tools
Display Modes


Similar M14 Forum Discussions
Thread Thread Starter Forum Replies Last Post
How to kick @$$ with m14 irons and grade 4 math Seven6Two The M14 78 January 23rd, 2016 12:09 AM
Long distance scope for the math challenged usndoc Optics 39 August 29th, 2012 03:23 AM



Top Gun Sites Top Sites List