[RDF-KY]

What does this mean? Does the lower spread mean the best? What does Standard Deviation mean? What is best when reloading?

[AikiDale]

Extreme spread is a reference to the fastest and slowest velocity measured by your chronograph. Standard Deviation is....look here: http://en.wikipedia....ndard_Deviation

[Flatland Shooter]

The lower the Standard Deviation the more consistent your loads are performing.

Where it comes into play is assisting you in selecting loads to make a certain power factor.

From information gleened from other sources on the forum, to assure 99%+ of your loads make major, you would want the velocity of your load to be 3 SD's higher than the minimum needed to make your power factor.

For a major load that uses 165 grain bullets you need a velocity of 1000 fps. If your chronograph indicates you have a SD of 10 fps, you would want to consider loads where the velocity is 1000 fps plus 3 times the SD of 10 for a velocity of 1030.

If your loads have a SD of 30 fps, you may need to load up at 1090 fps to be confident.

So a load with a low SD can be loaded closer to the 165 PF than a load with a high SD, and still be confident it will make major.

Bill

edited because I can't type when I'm sleepy. Good night.

This post has been edited by Flatland Shooter: 04 February 2008 - 11:40 PM