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
Chatting and General Stuff
General Discussion
Do Bullets Go To Sleep?
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="Michael Courtney" data-source="post: 835002" data-attributes="member: 28191"><p>Were the bullets keyholing, did you measure drag with two chronographs, or did you infer instability from group size? In my view, there are too many potentially confounding factors to reliably infer stability from group size, especially with the small sample sizes typically used by hobbyist reloaders.</p><p></p><p>Using sample size to indicate stability probable requires both working hard to remove and document all potentially confounding factors and measuring something like 10 five shot groups under each condition and reporting the mean group size and the standard deviation in the group size under each condition to determine if the difference in group sizes is significantly different (in the sense of a statistically significant difference), as well as reporting all the conditions of each measurement (temperature, humidity, ambient pressure, measured twist rate, bullet dimensions, etc.) </p><p></p><p>We've noticed that bullets from some lots are dimensionally different from other lots and can also have lengths and weights that vary from the manufacturer's published specs. Barrel twist rates can also vary from manufacturer specs and should be confirmed to accurately infer stability. Likewise, ambient conditions (temperature, humidity, barometric pressure) should be measured at the site with something like a Kestrel. Still, there are other factors like barrel fouling that can be hard to quantify or repeat exactly from one day to another.</p></blockquote><p></p>
[QUOTE="Michael Courtney, post: 835002, member: 28191"] Were the bullets keyholing, did you measure drag with two chronographs, or did you infer instability from group size? In my view, there are too many potentially confounding factors to reliably infer stability from group size, especially with the small sample sizes typically used by hobbyist reloaders. Using sample size to indicate stability probable requires both working hard to remove and document all potentially confounding factors and measuring something like 10 five shot groups under each condition and reporting the mean group size and the standard deviation in the group size under each condition to determine if the difference in group sizes is significantly different (in the sense of a statistically significant difference), as well as reporting all the conditions of each measurement (temperature, humidity, ambient pressure, measured twist rate, bullet dimensions, etc.) We've noticed that bullets from some lots are dimensionally different from other lots and can also have lengths and weights that vary from the manufacturer's published specs. Barrel twist rates can also vary from manufacturer specs and should be confirmed to accurately infer stability. Likewise, ambient conditions (temperature, humidity, barometric pressure) should be measured at the site with something like a Kestrel. Still, there are other factors like barrel fouling that can be hard to quantify or repeat exactly from one day to another. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Chatting and General Stuff
General Discussion
Do Bullets Go To Sleep?
Top