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Rifles, Reloading, Optics, Equipment
Reloading
Ugly extreme spread........now what ?
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<blockquote data-quote="Barrelnut" data-source="post: 1672350" data-attributes="member: 74902"><p>Good stuff above about getting 100 rounds thru the barrel and getting brass fire formed.</p><p>IMO, after all of that, you should try to get the SD down to 10 FPS or below. 5~7 FPS is a noble goal.</p><p>Looking at your numbers, the last one is way out of the norm and is probably caused by "climate change", so I would throw it away for now. If you use the rest of the numbers you get: Average = 2801 and SD = 15. Not toooo bad , but really more like factory ammo.</p><p>I can usually get my rounds down to to the 5~7 range by using fire formed brass without too much weight variance, annealing it each firing, and using accurate and consistent powder charges. even consistent weight and bearing surface of the bullets can help.</p><p>Standard deviation is easy to calculate in a spreadsheet. there are also SD calculators online.</p><p>Below is a link to an online SD calculator AND an excellent article on SD and just what it means and how much it matters.</p><p>For the 6.5 CM, I use H4350 for accurate target stuff, but a lot of shooters use RL16 in the 6.5 and have excellent results with it. RL16 is close to H4350 in burn rate and is supposed to be temp insensitive as well.</p><p></p><p>Online calc:</p><p><a href="https://www.calculator.net/standard-deviation-calculator.html" target="_blank">https://www.calculator.net/standard-deviation-calculator.html</a></p><p>PRB Blog Article on SD:</p><p><a href="https://precisionrifleblog.com/2015/04/18/how-much-does-sd-matter/" target="_blank">https://precisionrifleblog.com/2015/04/18/how-much-does-sd-matter/</a></p></blockquote><p></p>
[QUOTE="Barrelnut, post: 1672350, member: 74902"] Good stuff above about getting 100 rounds thru the barrel and getting brass fire formed. IMO, after all of that, you should try to get the SD down to 10 FPS or below. 5~7 FPS is a noble goal. Looking at your numbers, the last one is way out of the norm and is probably caused by "climate change", so I would throw it away for now. If you use the rest of the numbers you get: Average = 2801 and SD = 15. Not toooo bad , but really more like factory ammo. I can usually get my rounds down to to the 5~7 range by using fire formed brass without too much weight variance, annealing it each firing, and using accurate and consistent powder charges. even consistent weight and bearing surface of the bullets can help. Standard deviation is easy to calculate in a spreadsheet. there are also SD calculators online. Below is a link to an online SD calculator AND an excellent article on SD and just what it means and how much it matters. For the 6.5 CM, I use H4350 for accurate target stuff, but a lot of shooters use RL16 in the 6.5 and have excellent results with it. RL16 is close to H4350 in burn rate and is supposed to be temp insensitive as well. Online calc: [URL]https://www.calculator.net/standard-deviation-calculator.html[/URL] PRB Blog Article on SD: [URL]https://precisionrifleblog.com/2015/04/18/how-much-does-sd-matter/[/URL] [/QUOTE]
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Reloading
Ugly extreme spread........now what ?
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