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 RPM 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="Calamity" data-source="post: 2530690" data-attributes="member: 112048"><p>Physics texts refer to spin as angular velocity, and describe what we generally think of as centrifugal force (force trying to shed the bullet jacket) as centripetal force. It's just semantics, but I mention it in case you want to dig into it, and find the nomenclature confusing. Given that rotational speed (RPM) is determined by twist rate and velocity, the centripetal force is further determined by the diameter/radius of the bullet. Given a certain rotational speed, larger diameter bullets exert more force on the bullet jacket than slimmer diameter bullets, so a .44 bullet requires less rotational speed than a 6mm bullet, so you can't just pick an RPM number that is good for all calibers. Bullet designers can compensate for a range of RPMs by making jackets thicker, or using a stronger alloy like steel with copper plating. The bullet makers have taken these things into consideration for you, so using their calculators to check the range of bullet weights (their bullets) you intend to use for your caliber/velocity should dictate the most likely twist you need in a barrel. I hope this is helpful.</p></blockquote><p></p>
[QUOTE="Calamity, post: 2530690, member: 112048"] Physics texts refer to spin as angular velocity, and describe what we generally think of as centrifugal force (force trying to shed the bullet jacket) as centripetal force. It's just semantics, but I mention it in case you want to dig into it, and find the nomenclature confusing. Given that rotational speed (RPM) is determined by twist rate and velocity, the centripetal force is further determined by the diameter/radius of the bullet. Given a certain rotational speed, larger diameter bullets exert more force on the bullet jacket than slimmer diameter bullets, so a .44 bullet requires less rotational speed than a 6mm bullet, so you can't just pick an RPM number that is good for all calibers. Bullet designers can compensate for a range of RPMs by making jackets thicker, or using a stronger alloy like steel with copper plating. The bullet makers have taken these things into consideration for you, so using their calculators to check the range of bullet weights (their bullets) you intend to use for your caliber/velocity should dictate the most likely twist you need in a barrel. I hope this is helpful. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Bullet RPM and performance
Top