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Rifles, Reloading, Optics, Equipment
Reloading
Accuracy=seating depth or tenths of powder
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<blockquote data-quote="Pdvdh" data-source="post: 1114181" data-attributes="member: 4191"><p>Changing powder charges changes MV. Changing seating depths changes MV. Changing primers changes MV. Changing case capacity changes MV (different case weights = different internal volume). </p><p></p><p>Which causes me to revisit the possibility that what we're primarily doing is finding a MV that provides the best accuracy from our rifles. Both seating depth and powder charges affect MV. So how does anyone know which is what and what is which? Reminds me of the common Thermos. Keeps hot things hot and cold things cold. How does it know?</p><p></p><p>Historically I've primarily used different powder charges to find more accurate loads. I'm including seating depths more recently, particularly jammed 010" versus 0.010" jump for Berger bullets. Recently I changed seating depth in the search for lower ES and accuracy with RL33, which is known to produce higher ES with longer jumps - and lower ES with shorter jumps - to the lands. There is no change in the spectrum of seating depths that has a greater affect on MV/pressure than into - versus off - the lands 0.010". So I figured if shorter jump to the lands was the better approach to reduce ES, then jammed might be the best. The 215gr Berger Hybrids jammed 0.012" into the lands reduced my ES from 30-45fps to less than 10fps. This compared to a seating depth 0.005" - 0.010" off the lands. Accuracy was very similar at both seating depths. Of course, velocity/pressure both increased by jamming the bullets 0.012".</p><p></p><p>There are times when seating depth affects powder capacity to the point that I'm compressing powder charges (beyond my preference) to get to my preferred pressure/MV. And in those instances I prefer the longer seating depth if accuracy and ES is good. That was the case, and another consideration in the rifle with the 215gr Berger Hybrids.</p><p></p><p>I recently had another rifle where I was running out of powder capacity (excessive powder compression by bullet seating depth) prior to reaching maximum load pressures, so I switched from a standard LR primer (Fed 210) to a magnum LR primer (Fed 215). This was a 7mm Rem Mag. The change in primer had a similar affect on MV to a 1gr change in powder charge weight. The end result was all good. Accuracy was good and the bullets could be seated with very little powder compression.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1114181, member: 4191"] Changing powder charges changes MV. Changing seating depths changes MV. Changing primers changes MV. Changing case capacity changes MV (different case weights = different internal volume). Which causes me to revisit the possibility that what we're primarily doing is finding a MV that provides the best accuracy from our rifles. Both seating depth and powder charges affect MV. So how does anyone know which is what and what is which? Reminds me of the common Thermos. Keeps hot things hot and cold things cold. How does it know? Historically I've primarily used different powder charges to find more accurate loads. I'm including seating depths more recently, particularly jammed 010" versus 0.010" jump for Berger bullets. Recently I changed seating depth in the search for lower ES and accuracy with RL33, which is known to produce higher ES with longer jumps - and lower ES with shorter jumps - to the lands. There is no change in the spectrum of seating depths that has a greater affect on MV/pressure than into - versus off - the lands 0.010". So I figured if shorter jump to the lands was the better approach to reduce ES, then jammed might be the best. The 215gr Berger Hybrids jammed 0.012" into the lands reduced my ES from 30-45fps to less than 10fps. This compared to a seating depth 0.005" - 0.010" off the lands. Accuracy was very similar at both seating depths. Of course, velocity/pressure both increased by jamming the bullets 0.012". There are times when seating depth affects powder capacity to the point that I'm compressing powder charges (beyond my preference) to get to my preferred pressure/MV. And in those instances I prefer the longer seating depth if accuracy and ES is good. That was the case, and another consideration in the rifle with the 215gr Berger Hybrids. I recently had another rifle where I was running out of powder capacity (excessive powder compression by bullet seating depth) prior to reaching maximum load pressures, so I switched from a standard LR primer (Fed 210) to a magnum LR primer (Fed 215). This was a 7mm Rem Mag. The change in primer had a similar affect on MV to a 1gr change in powder charge weight. The end result was all good. Accuracy was good and the bullets could be seated with very little powder compression. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Accuracy=seating depth or tenths of powder
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