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Topic: BC. How does weight affect it?  (Read 3719 times) previous topic - next topic

Re: BC. How does weight affect it?

Reply #30
 WHM ; awesome article. 
There was 1 sentence in there that speaks to my queri,  tho both articles are chock full of great information. 

If 2 bullets have the same BC choose the lighter one.

This seems to run contrary to the emphasis of the articles.  . However on rereading them I don't think it is. .
It will be very interesting to see how the GS SP 112 compares to the 140 gr bullets with similar BC numbers. 

Thank you!
If your going to be a Bush Alaskan You need a perfect winter rifle. The Ruger M77 Hawkeye SS in 6.5 Creedmoor is mine.<br>You are being watched.

Re: BC. How does weight affect it?

Reply #31
ctf, you and rainier are the only shooters i know using these bullets and i have heard a lot of good things about them and in theory it may prove true. i am very excited in keeping up with yalls actual findings and see the groups and velocities.
ps  you are NOT ignorant, if you don't know just ask. and sort thru all the information and decide for yourself. after this thread im sure there's a few things i have learned myself. thanks men.
"kill em all"

Re: BC. How does weight affect it?

Reply #32
I was ignorant of SSOOOO much to do with putting a bullet where I want it at long range.  I'm now not Quite so ignorant  . Being ignorant of something just means not knowing.  Nothin wrong with that.  But Rejecting knowledge.  Now that is IMO,  Ignorance!  So I have found that if I can ask the right people the right questions especially in a public setting like this. Not only do I learn,  hopefully others do also.   ;D
If your going to be a Bush Alaskan You need a perfect winter rifle. The Ruger M77 Hawkeye SS in 6.5 Creedmoor is mine.<br>You are being watched.

Re: BC. How does weight affect it?

Reply #33
 In those 2 articals.  He talked about retained velocity and reduced wind drift.  He doesn't talk about drop. Which could be taken care of by having enough elevation in the scope.  I need to go reread them again.  I really appreciate you posting them WHM.  !
If your going to be a Bush Alaskan You need a perfect winter rifle. The Ruger M77 Hawkeye SS in 6.5 Creedmoor is mine.<br>You are being watched.

Re: BC. How does weight affect it?

Reply #34
CTF - Here's some info and a picture from some guy named Germán A. Salazar you might find interesting...

Quote
The Magic Numbers
The single biggest challenge in long-range shooting with a .308 is keeping the bullet above the transonic range as it reaches the target. Once it dips into that velocity range, accuracy will be compromised and in many cases the bullet will become unstable and a potential danger to the target marking crew. In light of the foregoing, our primary concern is keeping the bullet out of that transonic range and the first magic number that we must keep in mind is 1.2 mach (1.2 times the speed of sound). The speed of sound through air varies with atmospheric conditions; accordingly, there is no absolute velocity for 1.2 mach, it will depend upon the conditions present at the range where you shoot.





"Truth is treason in the empire of lies" - Ron Paul

Re: BC. How does weight affect it?

Reply #35

I was ignorant of SSOOOO much to do with putting a bullet where I want it at long range.  I'm now not Quite so ignorant  . Being ignorant of something just means not knowing.  Nothin wrong with that.  But Rejecting knowledge.  Now that is IMO,  Ignorance!  So I have found that if I can ask the right people the right questions especially in a public setting like this. Not only do I learn,  hopefully others do also.  

Like to ring an echo here
Have learnt a lot since joining this forum
The group of guys on here are quite different to a lot of forums.
Not so much to prove but plenty to share.
Don't look down on people unless you're helping them up.

Re: BC. How does weight affect it?

Reply #36
I am so glad that you found this, this is what I have been trying to relay to others as to WHY I was in search of the 1700fps mark. I knew the printed information was out there because ive seen it before but just couldn't put my finger on it.
on the east coast where I do a lot of shooting in similar conditions I am in the 1580 -1630 to 40 fps range at 1000, which shoots really good with 5in groups but I feel if I get a 140 with a .618bc to the 1700mark I MAY be able to reach my goal of sub 3in groups at 1000. at least that's the plan anyway.
"kill em all"

Re: BC. How does weight affect it?

Reply #37
Ballistic Coefficient is comprised of three components: mass, cross sectional area, and drag... Read this article from Appliedballastics and your questions about weight and BC will be answered.  http://www.appliedballisticsllc.com/index_files/30cal_fullVersion.pdf

It also explaines why the 6.5 is the go to caliber.

Re: BC. How does weight affect it?

Reply #38
 I knew there was a good reason I chose the Creedmoor. 
Excellent article. Thank you for posting it. 

So according to his article, Sectional Density.  Plays an important roll in down range ballistics. 
If your going to be a Bush Alaskan You need a perfect winter rifle. The Ruger M77 Hawkeye SS in 6.5 Creedmoor is mine.<br>You are being watched.

Re: BC. How does weight affect it?

Reply #39
http://www.gsgroup.co.za/winddrift.html


Then there is this
If your going to be a Bush Alaskan You need a perfect winter rifle. The Ruger M77 Hawkeye SS in 6.5 Creedmoor is mine.<br>You are being watched.

Re: BC. How does weight affect it?

Reply #40

Ballistic Coefficient is comprised of three components: mass, cross sectional area, and drag... Read this article from Appliedballastics and your questions about weight and BC will be answered.  http://www.appliedballisticsllc.com/index_files/30cal_fullVersion.pdf

It also explaines why the 6.5 is the go to caliber.


Thanks for the share! I just ordered the book and program. So much for listening to you guys!  ;D

Re: BC. How does weight affect it?

Reply #41
Two bullets with the same bc but different weights are going to fly the same, what the heaver bullet lacks in aerodynamics it makes up for in mass, and vis versa for the lighter one. Something to consider is the bc of a bullet is calculated by it's forward movement, if one of the bullets has a larger side profile it will b effected by a cross wind more than a bullet with a smaller side profile.

Re: BC. How does weight affect it?

Reply #42
Logan ; welcome to the 6.5 Creedmoor forum  . !!
If your going to be a Bush Alaskan You need a perfect winter rifle. The Ruger M77 Hawkeye SS in 6.5 Creedmoor is mine.<br>You are being watched.