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
Bullet Spin and Performance
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="BryanLitz" data-source="post: 248646" data-attributes="member: 7848"><p>I have a program that calculates the stability factor for a bullet based on Don Miller's formula. For those unfamiliar with Don's work, he's been publishing it in PS magazine for years. I believe his stability formula is very accurate, and a huge contribution to exterior ballistics as it updates the old Greenhill formula which is still often used, but incorrect for modern bullets.</p><p>Anyone who would like a copy of the program can email me at: </p><p><a href="mailto:bsl135@yahoo.com">bsl135@yahoo.com</a></p><p>and I will send the program to you in a email attachment.</p><p></p><p>meichele states above that a stability factor of 1.5 is 'optimal'. I won't argue that, but will point out that it isn't a fixed rule. I've seen stability factors from 1.3 to 1.5 suggested as 'minimal required', meaning optimal. Using a faster twist than that required to achieve an Sg of 1.3 to 1.5 isn't as consequential as many think in terms of 'overstabilization'. You do get more spin drift from a bullet with a higher Sg, but it's no less accurate, and doesn't erode the BC as much as some think. </p><p>The worst thing that happens when you spin a bullet too fast is that you exaggerate any dispersion components that are caused by spin. For example, a bullet with a cg offset will have more dispersion if it emerges from the muzzle with greater spin. In this case, the extra dispersion isn't a consequence of higher stability, but simply a byproduct of spinning faster, regardless of Sg. Using well made bullets, and minimizing in-bore yaw will mitigate the dispersion related to spin rate.</p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 248646, member: 7848"] I have a program that calculates the stability factor for a bullet based on Don Miller's formula. For those unfamiliar with Don's work, he's been publishing it in PS magazine for years. I believe his stability formula is very accurate, and a huge contribution to exterior ballistics as it updates the old Greenhill formula which is still often used, but incorrect for modern bullets. Anyone who would like a copy of the program can email me at: [email]bsl135@yahoo.com[/email] and I will send the program to you in a email attachment. meichele states above that a stability factor of 1.5 is 'optimal'. I won't argue that, but will point out that it isn't a fixed rule. I've seen stability factors from 1.3 to 1.5 suggested as 'minimal required', meaning optimal. Using a faster twist than that required to achieve an Sg of 1.3 to 1.5 isn't as consequential as many think in terms of 'overstabilization'. You do get more spin drift from a bullet with a higher Sg, but it's no less accurate, and doesn't erode the BC as much as some think. The worst thing that happens when you spin a bullet too fast is that you exaggerate any dispersion components that are caused by spin. For example, a bullet with a cg offset will have more dispersion if it emerges from the muzzle with greater spin. In this case, the extra dispersion isn't a consequence of higher stability, but simply a byproduct of spinning faster, regardless of Sg. Using well made bullets, and minimizing in-bore yaw will mitigate the dispersion related to spin rate. -Bryan [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet Spin and Performance
Top