Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Chronographs: What to do?
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="ilc" data-source="post: 1799524" data-attributes="member: 97996"><p>Even if you used a G1 or G7 BC that has been accurately calculated to three decimal points by Litz, it still might not be good enough to get you on target at long range. The reason is because the BC is not a drag function for your projectile, it is a scaling factor applied to another "standard" projectile, which will have different ballistics to yours.</p><p></p><p>100 years or so ago, before electronic chronographs and radar, establishing a drag curve for a projectile was a slow and complicated process. To make things easier they settled on a few different standardised projectiles, established their drag curves, and for all other projectiles they multiplied these standard curves by a scaling factor called the Ballistic Coefficient.</p><p></p><p>For many years commercial bullet makers compared their projectiles to the G1 standard, and based their BCs on the G1 drag curve. The problem with this is that the G1 projectile is fairly blunt, and not a good representation of modern streamlined projectiles. To get around this some manufacturers quoted multiple BCs for different speed zones, to better match their projectile to the G1 drag function.</p><p></p><p>Litz, and maybe others, popularised the fact that the G7 standard projectile (which is a sharp, streamlined shape) was a better approximation for modern long range bullets, so he set about with his AB team accurately measuring G1 and G7 BCs for Berger and other commercial bullets.</p><p></p><p>The problem remained however, that the G7 model was still not an exact model for all the bullets he was measuring, maybe not accurate enough to get you on target at long range. He got around this problem by using radar to measure the entire drag curve of each individual bullet. If you use the AB software it includes these custom drag functions for many bullets.</p><p></p><p>However, it was then discovered that the BC of a given bullet can vary between different rifles. For example, twist rate and stability can effect the BC. Litz and AB now get around this limitation with their mobile ballistics lab by measuring your particular load in your rifle, and giving you an individualised custom drag curve. Even still, their measured BC varies slightly from shot to shot with the same bullet, in the same rifle.</p><p></p><p>So I guess the moral of this story is that there is some inevitable variation and inaccuracy in ballistic calculations. Then you have to deal with the environment....</p></blockquote><p></p>
[QUOTE="ilc, post: 1799524, member: 97996"] Even if you used a G1 or G7 BC that has been accurately calculated to three decimal points by Litz, it still might not be good enough to get you on target at long range. The reason is because the BC is not a drag function for your projectile, it is a scaling factor applied to another "standard" projectile, which will have different ballistics to yours. 100 years or so ago, before electronic chronographs and radar, establishing a drag curve for a projectile was a slow and complicated process. To make things easier they settled on a few different standardised projectiles, established their drag curves, and for all other projectiles they multiplied these standard curves by a scaling factor called the Ballistic Coefficient. For many years commercial bullet makers compared their projectiles to the G1 standard, and based their BCs on the G1 drag curve. The problem with this is that the G1 projectile is fairly blunt, and not a good representation of modern streamlined projectiles. To get around this some manufacturers quoted multiple BCs for different speed zones, to better match their projectile to the G1 drag function. Litz, and maybe others, popularised the fact that the G7 standard projectile (which is a sharp, streamlined shape) was a better approximation for modern long range bullets, so he set about with his AB team accurately measuring G1 and G7 BCs for Berger and other commercial bullets. The problem remained however, that the G7 model was still not an exact model for all the bullets he was measuring, maybe not accurate enough to get you on target at long range. He got around this problem by using radar to measure the entire drag curve of each individual bullet. If you use the AB software it includes these custom drag functions for many bullets. However, it was then discovered that the BC of a given bullet can vary between different rifles. For example, twist rate and stability can effect the BC. Litz and AB now get around this limitation with their mobile ballistics lab by measuring your particular load in your rifle, and giving you an individualised custom drag curve. Even still, their measured BC varies slightly from shot to shot with the same bullet, in the same rifle. So I guess the moral of this story is that there is some inevitable variation and inaccuracy in ballistic calculations. Then you have to deal with the environment.... [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Chronographs: What to do?
Top