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
Reloading
How critical is measuring powder to .01 grains
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="MKWas" data-source="post: 2784935" data-attributes="member: 106445"><p>Accuracy vs Precision. In metrology the two terms mean very different things. It is important to know both.</p><p></p><p>Accuracy is how close a measurement is to the real value. If you have a 100 grain weight does your scale actually read 100 grains? since there is some variation you need to take multiple readings & average. A scale that measures 100 3 times is as accurate as one that measures 90, 100, 110. One that measures 110 3 times is less accurate than the other two. For a first pass, a scale that measures to 0.01 gr is 10 times as accurate as one that measures to .01 gr. Maybe!</p><p></p><p>Precision is how close repeated measurements are. For the examples above: the one that measures 100 3 times & the one that measures 110 3 times have the same precision, the one that measures 90, 100, 110 is least precise.</p><p></p><p>So what you really want is precision - reload with the same load with the same equipment and you have repeatability. You can't ignore accuracy, but as long as you are within +/-0.1 grains you are probably OK especially for most rifle loads.</p><p></p><p>An easy thing to do is to get a box of representative bullets: </p><p>- Measure a bullet repeatedly, is it always the same? </p><p>- Try several - they won't all be the same weight but most should measure the same weight every time. </p><p>- Some will be not measure the same every time. These are bullets actual weights are between what can be displayed - if your scale measures to 0.1 gr then that means the bullet's weight close to xxx.05 gr. The fluctuation indicates precision. I wouldn't expect any to measure 3 different weights.</p><p>- Repeat several times.</p><p></p><p>Evaluation:</p><p>- If you have any bullet that reads 3 different weights then the scale is highly suspect. That is, if you get readings 99.1, 99.2 & 99.3 on the same bullet then the accuracy is highly suspect. I wouldn't trust that scale.</p><p>- The fewer bullets with weight fluctuation the better your precision.</p><p></p><p>This gives a subjective evaluation. Anything more requires expensive equipment & specialized expertise. </p><p></p><p>You may want to keep the bullets that have variation. See if you get the same results under different conditions - like low charge/batteries, different ambient temperatures.</p></blockquote><p></p>
[QUOTE="MKWas, post: 2784935, member: 106445"] Accuracy vs Precision. In metrology the two terms mean very different things. It is important to know both. Accuracy is how close a measurement is to the real value. If you have a 100 grain weight does your scale actually read 100 grains? since there is some variation you need to take multiple readings & average. A scale that measures 100 3 times is as accurate as one that measures 90, 100, 110. One that measures 110 3 times is less accurate than the other two. For a first pass, a scale that measures to 0.01 gr is 10 times as accurate as one that measures to .01 gr. Maybe! Precision is how close repeated measurements are. For the examples above: the one that measures 100 3 times & the one that measures 110 3 times have the same precision, the one that measures 90, 100, 110 is least precise. So what you really want is precision - reload with the same load with the same equipment and you have repeatability. You can't ignore accuracy, but as long as you are within +/-0.1 grains you are probably OK especially for most rifle loads. An easy thing to do is to get a box of representative bullets: - Measure a bullet repeatedly, is it always the same? - Try several - they won't all be the same weight but most should measure the same weight every time. - Some will be not measure the same every time. These are bullets actual weights are between what can be displayed - if your scale measures to 0.1 gr then that means the bullet's weight close to xxx.05 gr. The fluctuation indicates precision. I wouldn't expect any to measure 3 different weights. - Repeat several times. Evaluation: - If you have any bullet that reads 3 different weights then the scale is highly suspect. That is, if you get readings 99.1, 99.2 & 99.3 on the same bullet then the accuracy is highly suspect. I wouldn't trust that scale. - The fewer bullets with weight fluctuation the better your precision. This gives a subjective evaluation. Anything more requires expensive equipment & specialized expertise. You may want to keep the bullets that have variation. See if you get the same results under different conditions - like low charge/batteries, different ambient temperatures. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
How critical is measuring powder to .01 grains
Top