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Rifles, Reloading, Optics, Equipment
Reloading
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<blockquote data-quote="MagnumManiac" data-source="post: 2107441" data-attributes="member: 10755"><p>Burn rate charts are a guess at best and have virtually zero correlation to how a powder burns in a given CARTRIDGE.</p><p>Burn rate is NOT CONSTANT, this is why powders on a burn rate chart do not correlate with the same velocities or pressures. Also, there is no set STANDARD to which each manufacturer sets the base powder, so they can be very different to what's listed.</p><p>An example, straight wall cartridges like the 458 Lott exhibit best performance with middle burn rate powders that are fast for the case volume, but this is due to the nature of straight walled cases causing a powder to behave much slower in burn than in a bottle necked case.</p><p>If you try to burn a slow powder in a straight walled case, the pressure doesn't develop because the bullet outruns the pressure/gas volume and the powder fizzles and dies out. If there is not enough start pressure, the powder can't catch up and burn fast enough to fill the void behind the bullet, just like an over fuelled cylinder, it just can't burn in the volume provided.</p><p></p><p>I would place very little validation on burn rate charts.</p><p>The easiest method to determine a suitable powder is to look at several load data sources and choose the powders that are listed most frequently in the top 3-4 that produce the highest velocities, this means that they're the most efficient powders for that cartridge.</p><p></p><p>Cheers.</p></blockquote><p></p>
[QUOTE="MagnumManiac, post: 2107441, member: 10755"] Burn rate charts are a guess at best and have virtually zero correlation to how a powder burns in a given CARTRIDGE. Burn rate is NOT CONSTANT, this is why powders on a burn rate chart do not correlate with the same velocities or pressures. Also, there is no set STANDARD to which each manufacturer sets the base powder, so they can be very different to what’s listed. An example, straight wall cartridges like the 458 Lott exhibit best performance with middle burn rate powders that are fast for the case volume, but this is due to the nature of straight walled cases causing a powder to behave much slower in burn than in a bottle necked case. If you try to burn a slow powder in a straight walled case, the pressure doesn’t develop because the bullet outruns the pressure/gas volume and the powder fizzles and dies out. If there is not enough start pressure, the powder can’t catch up and burn fast enough to fill the void behind the bullet, just like an over fuelled cylinder, it just can’t burn in the volume provided. I would place very little validation on burn rate charts. The easiest method to determine a suitable powder is to look at several load data sources and choose the powders that are listed most frequently in the top 3-4 that produce the highest velocities, this means that they’re the most efficient powders for that cartridge. Cheers. [/QUOTE]
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