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Rifles, Reloading, Optics, Equipment
Reloading
Why start at 10% below maximum?
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<blockquote data-quote="BountyHunter" data-source="post: 536173" data-attributes="member: 12"><p>There are several reasons for what you are seeing.</p><p> </p><p>1. The data in the manual is ONLY accurate in that particular gun chamber, with that throat, etc that they tested the loads and listed in the manual. Want to blow your mind, compare different manuals from different sources and even previous editions. </p><p> </p><p>2. Component variation will cause pressue to go up or down. Pressure testing has shown that changing primers alone can raise pressures over 5000 psi. Plus with many powders you have lot to lot pressure variations. Did they test a slow or fast lot? That is also why they tell you when you change components to start over. </p><p> </p><p>That why I love the Quick Load "experts" that jump out and say this load is over pressure or not based on their doodling with QL. If you talk to QL techs, they will tell you it is an average and cannot be applied to specfic guns that are outside their test parameters they used to determine their data. You can go into QL afterwards and adjust certain parameters to equal what you are showing in testing. When someone posts a QL chart, you do not know what the internal parameters are set and and you can vary pressue printouts by over 7000 psi by that alone for the exact same load if you do not watch it. Done it and seen it erroneously done on this board. It is just another tool to give you starting indicatores that can ONLY be validated as accurate by pressure testing with a strain gauge. No one outside of labs is using copper CUPS anymore.</p><p> </p><p>3. Lot of old guns out there that are weaker in action strength than modern guns, yet they are chambered in most of the modern calibers. ie 98 mausers for example.</p><p> </p><p>4. Flattened primers by themselves is not a reliable indicator of pressure or absence of pressure. Primer cup hardness greatly varies between brands. Good example is everyone has learned to use the CCI 450 primer in the BR cases because of that to prevent primer piercing and flow.</p><p> </p><p>5. Using just visual indicators of pressure, it is difficult to actually determine what is under max SAAMI pressure. Without an accurate pressure guage it is a guessing game where you have to rely on the total sum of indicators not just one. You cannot say, load until the bolt locks and then back off two grains for example as some say. You have to look at all of them and understand when you see the totality of pressure indicators, you know you are over but not how far or in their absence, how far you are under.</p><p> </p><p>6. Load manuals are based soley off rounds loaded to no more than max COAL for hunting purposes. Put a bullet into the lands, as many do here and pressures jump with the same load. </p><p> </p><p>7. Always start testing from one of two points: IF it is a magazine gun, start at max COAL. If it is a single shot, start into the lands. You only have one way to go; back!!!</p><p> </p><p>Build a load that is accurate as you want and need, and as fast as you think is reasonable and be happy. Is 50 fps going to make or break a LR shot? Doubt it. </p><p> </p><p>BH</p></blockquote><p></p>
[QUOTE="BountyHunter, post: 536173, member: 12"] There are several reasons for what you are seeing. 1. The data in the manual is ONLY accurate in that particular gun chamber, with that throat, etc that they tested the loads and listed in the manual. Want to blow your mind, compare different manuals from different sources and even previous editions. 2. Component variation will cause pressue to go up or down. Pressure testing has shown that changing primers alone can raise pressures over 5000 psi. Plus with many powders you have lot to lot pressure variations. Did they test a slow or fast lot? That is also why they tell you when you change components to start over. That why I love the Quick Load "experts" that jump out and say this load is over pressure or not based on their doodling with QL. If you talk to QL techs, they will tell you it is an average and cannot be applied to specfic guns that are outside their test parameters they used to determine their data. You can go into QL afterwards and adjust certain parameters to equal what you are showing in testing. When someone posts a QL chart, you do not know what the internal parameters are set and and you can vary pressue printouts by over 7000 psi by that alone for the exact same load if you do not watch it. Done it and seen it erroneously done on this board. It is just another tool to give you starting indicatores that can ONLY be validated as accurate by pressure testing with a strain gauge. No one outside of labs is using copper CUPS anymore. 3. Lot of old guns out there that are weaker in action strength than modern guns, yet they are chambered in most of the modern calibers. ie 98 mausers for example. 4. Flattened primers by themselves is not a reliable indicator of pressure or absence of pressure. Primer cup hardness greatly varies between brands. Good example is everyone has learned to use the CCI 450 primer in the BR cases because of that to prevent primer piercing and flow. 5. Using just visual indicators of pressure, it is difficult to actually determine what is under max SAAMI pressure. Without an accurate pressure guage it is a guessing game where you have to rely on the total sum of indicators not just one. You cannot say, load until the bolt locks and then back off two grains for example as some say. You have to look at all of them and understand when you see the totality of pressure indicators, you know you are over but not how far or in their absence, how far you are under. 6. Load manuals are based soley off rounds loaded to no more than max COAL for hunting purposes. Put a bullet into the lands, as many do here and pressures jump with the same load. 7. Always start testing from one of two points: IF it is a magazine gun, start at max COAL. If it is a single shot, start into the lands. You only have one way to go; back!!! Build a load that is accurate as you want and need, and as fast as you think is reasonable and be happy. Is 50 fps going to make or break a LR shot? Doubt it. BH [/QUOTE]
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Why start at 10% below maximum?
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