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
LoadBase? Miller or Greenhill Method?
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: 341830" data-attributes="member: 7848"><p>Unless your bullet is a round nose, flat base bullet with a muzzle velocity of ~1400 fps or less, the Greenhill formula is not the one to use.</p><p></p><p>The Miller formula is tailored for modern bullets at high velocities and will give much better stability predictions than Greenhill.</p><p></p><p>Having said that, if all your inputs are right and it suggests you're 'understabilized' for the bullets you shoot great groups with, the following are things to think about:</p><p></p><p>1) The formula isn't 100% perfect.</p><p>2) The thresh-hold for a 'safe' margin of stability is subjective. Some say a stability factor of 1.5 is required, some say 1.3. I go with 1.4.</p><p>3) Your barrel may have a faster twist than you think.</p><p>4) Are you shooting at high altitude, and is this reflected in the stability calculation you did?</p><p></p><p>Just some thoughts that might rectify the calculations and observations.</p><p></p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 341830, member: 7848"] Unless your bullet is a round nose, flat base bullet with a muzzle velocity of ~1400 fps or less, the Greenhill formula is not the one to use. The Miller formula is tailored for modern bullets at high velocities and will give much better stability predictions than Greenhill. Having said that, if all your inputs are right and it suggests you're 'understabilized' for the bullets you shoot great groups with, the following are things to think about: 1) The formula isn't 100% perfect. 2) The thresh-hold for a 'safe' margin of stability is subjective. Some say a stability factor of 1.5 is required, some say 1.3. I go with 1.4. 3) Your barrel may have a faster twist than you think. 4) Are you shooting at high altitude, and is this reflected in the stability calculation you did? Just some thoughts that might rectify the calculations and observations. -Bryan [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
LoadBase? Miller or Greenhill Method?
Top