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Rifles, Reloading, Optics, Equipment
Reloading
Why do I need so much powder?
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<blockquote data-quote="Dean2" data-source="post: 2251565" data-attributes="member: 26077"><p>You have multiple variables at work;</p><p>Changed powder lots</p><p>Barrel has 300 rounds fired or 50% used</p><p>You are using different Chronographs</p><p>Air Temp changes</p><p>Humidity changes</p><p>Virgin brass to 3x fired</p><p>Varying neck tension due to work hardening</p><p>It isn't real clear from your posts as to the seating depths being the same. If you are seating them further out to maintain relationship to lands, you are increasing case capacity, and dropping pressure.</p><p>Have you tested the scale and are you using the same scale.</p><p></p><p>With this many factors, and the potential that a number of them are in play at the same time, I have no problem seeing a 100 fps velocity change. What is a little surprising is that it takes almost 2.5 - 4 grains to pick up 100 fps. Min to max published loads are only 4 to 5 grains apart and are over 200 fps different in that increase. You are running 169 Hammers at 3300 fps and 180 Bergers at almost 3200 fps, so I would say you have passed max load. I think you may be at the load point where velocity has plateaued and adding more powder does not increase velocity by any significant amount. That is usually a very clear sign that you should back off at least a couple of grains and call it good.</p><p></p><p>This is Berger's Load data for their 175 grain bullets. <strong>You are almost 5 grains PAST suggested max load with the 180s alone, and almost 100 fps faster than the Berger 175 loads.</strong>.</p><p></p><p>28 Nosler</p><p>175 Grain</p><p>Barrel Length = 26"</p><p>COAL = 3.417"</p><p>Optimal performance may be achieved in your rifle</p><p>at a different COAL. Read HERE for details.</p><p>175 gr Elite hunter</p><p>G1 BC = 0.656 G7 BC = 0.336</p><p>Part # 28554 - 1 in 9" twist or faster</p><p>For bullet dimensional details, click HERE.</p><p>warning - Approach maximum loads with caution as all rifles and</p><p>reloading techniques will be different.</p><p>Additional safety information can be found HERE.</p><p>Powder Start</p><p>Load</p><p>Approx.</p><p>Start Vel.</p><p>Max</p><p>Load</p><p>Approx.</p><p>Max Vel.</p><p>Approx.</p><p>Fill Ratio</p><p>IMR 7828 69.0 2888 72.8 3035 94%</p><p>AA Magpro 72.5 2892 76.4 3043 90%</p><p>RETUMBO 77.0 2911 81.3 3066 101%</p><p>NORMA 217 77.0 2906 81.3 3066 103%</p><p>VIHT N570 78.0 2936 82.3 3114 98%</p><p>RE-33 82.0 2927 86.3 3103 100%</p><p>We recommend using G7 BC to achieve the most</p><p>accurate trajectory prediction.</p></blockquote><p></p>
[QUOTE="Dean2, post: 2251565, member: 26077"] You have multiple variables at work; Changed powder lots Barrel has 300 rounds fired or 50% used You are using different Chronographs Air Temp changes Humidity changes Virgin brass to 3x fired Varying neck tension due to work hardening It isn't real clear from your posts as to the seating depths being the same. If you are seating them further out to maintain relationship to lands, you are increasing case capacity, and dropping pressure. Have you tested the scale and are you using the same scale. With this many factors, and the potential that a number of them are in play at the same time, I have no problem seeing a 100 fps velocity change. What is a little surprising is that it takes almost 2.5 - 4 grains to pick up 100 fps. Min to max published loads are only 4 to 5 grains apart and are over 200 fps different in that increase. You are running 169 Hammers at 3300 fps and 180 Bergers at almost 3200 fps, so I would say you have passed max load. I think you may be at the load point where velocity has plateaued and adding more powder does not increase velocity by any significant amount. That is usually a very clear sign that you should back off at least a couple of grains and call it good. This is Berger's Load data for their 175 grain bullets. [B]You are almost 5 grains PAST suggested max load with the 180s alone, and almost 100 fps faster than the Berger 175 loads.[/B]. 28 Nosler 175 Grain Barrel Length = 26” COAL = 3.417” Optimal performance may be achieved in your rifle at a different COAL. Read HERE for details. 175 gr Elite hunter G1 BC = 0.656 G7 BC = 0.336 Part # 28554 - 1 in 9” twist or faster For bullet dimensional details, click HERE. warning - Approach maximum loads with caution as all rifles and reloading techniques will be different. Additional safety information can be found HERE. Powder Start Load Approx. Start Vel. Max Load Approx. Max Vel. Approx. Fill Ratio IMR 7828 69.0 2888 72.8 3035 94% AA Magpro 72.5 2892 76.4 3043 90% RETUMBO 77.0 2911 81.3 3066 101% NORMA 217 77.0 2906 81.3 3066 103% VIHT N570 78.0 2936 82.3 3114 98% RE-33 82.0 2927 86.3 3103 100% We recommend using G7 BC to achieve the most accurate trajectory prediction. [/QUOTE]
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