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Rifles, Reloading, Optics, Equipment
Reloading
Trying to understand sd and es in load development
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<blockquote data-quote="timotheius" data-source="post: 1572994" data-attributes="member: 66591"><p>So I recently got a Magnetospeed chronograph and have been using it to try to develop an accurate load for varmint/predator hunting with my AR-15. I am using 50 grain sierras, 8208 XBR powder, lapua brass. I started with 24.5 grains, and I loaded up 4 round groups in .3 grain increments and then tested their accuracy and speed. So what exactly is the role of SD and ES in load development? I guess my question is this: will the 4 round group with lowest Standard Deviation and Extreme Spread always be the best load for the rifle? Or is it possible that groups with higher SD and ES might be the better accuracy load? Would I be better off just firing off rounds looking for the low SD without much regard for where they land on paper initially? I have found a few charge weights that shot great looking sub-moa groups, but the SD was about 30. I had one group where the SD was around 10, but the 4 shots were scattered all over the place. My best group had an SD of 8, but was at 26.5 grains which I feel was probably over max.</p></blockquote><p></p>
[QUOTE="timotheius, post: 1572994, member: 66591"] So I recently got a Magnetospeed chronograph and have been using it to try to develop an accurate load for varmint/predator hunting with my AR-15. I am using 50 grain sierras, 8208 XBR powder, lapua brass. I started with 24.5 grains, and I loaded up 4 round groups in .3 grain increments and then tested their accuracy and speed. So what exactly is the role of SD and ES in load development? I guess my question is this: will the 4 round group with lowest Standard Deviation and Extreme Spread always be the best load for the rifle? Or is it possible that groups with higher SD and ES might be the better accuracy load? Would I be better off just firing off rounds looking for the low SD without much regard for where they land on paper initially? I have found a few charge weights that shot great looking sub-moa groups, but the SD was about 30. I had one group where the SD was around 10, but the 4 shots were scattered all over the place. My best group had an SD of 8, but was at 26.5 grains which I feel was probably over max. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Trying to understand sd and es in load development
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