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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Barrel length and powder burn rates?
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<blockquote data-quote="AJ Peacock" data-source="post: 287189" data-attributes="member: 4885"><p>Yes, as the bullet goes down the barrel, the gas has to expand. The pressure will drop. This is known as Boyles law. Boyles law is a special case of the ideal gas law that deals with systems that have a constant temperature. Now, in your universe, the powder is all burnt, so the temperature has to be dropping; check the Ideal Gas Law, this lowering of the temperature will also cause a drop in pressure. Without decreasing the volume (can't happen as the bullet progresses down the barrel) or increasing the temperature (can't happen in your world, as the powder is all burnt already) or increasing the amount of gas (can't happen in your world if the powder is all burnt), the pressure has to precipitously drop as the volume increases. According to your supposition, long barrels would tend to slow a bullet down. A 22LR will slow down after about 16" of barrel length due to this affect. We use slower powders to keep this from happening in our centerfire rifles.</p><p></p><p>If however, something other than the Ideal Gas Law is working <strong>AFTER</strong> the powder is burnt, please let us know. The law is only about 400yrs old, so maybe it hasn't been fully investigated and is actually incorrect<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite11" alt=":rolleyes:" title="Roll Eyes :rolleyes:" loading="lazy" data-shortname=":rolleyes:" />.</p><p></p><p></p><p></p><p></p><p>Enlighten us with the calibers you are reloading with slow powders and short barrels. Let us know how it is working for you. If the powder is all burnt, why are you loosing speed? Wouldn't fast and slow powders work the same, regardless of which powder you use in a short barrel?</p><p></p><p>You can't have it both ways, either the powder is burnt and should all work the same, or it isn't burnt and that is why you are loosing velocity (and this argument <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" />)</p><p></p><p></p><p>Unless, you agree with #1 on my previous post. If this is the case, then let us know. You never responded to my question, trying to clarify your position.</p><p></p><p>Thanks,</p><p>AJ</p></blockquote><p></p>
[QUOTE="AJ Peacock, post: 287189, member: 4885"] Yes, as the bullet goes down the barrel, the gas has to expand. The pressure will drop. This is known as Boyles law. Boyles law is a special case of the ideal gas law that deals with systems that have a constant temperature. Now, in your universe, the powder is all burnt, so the temperature has to be dropping; check the Ideal Gas Law, this lowering of the temperature will also cause a drop in pressure. Without decreasing the volume (can't happen as the bullet progresses down the barrel) or increasing the temperature (can't happen in your world, as the powder is all burnt already) or increasing the amount of gas (can't happen in your world if the powder is all burnt), the pressure has to precipitously drop as the volume increases. According to your supposition, long barrels would tend to slow a bullet down. A 22LR will slow down after about 16" of barrel length due to this affect. We use slower powders to keep this from happening in our centerfire rifles. If however, something other than the Ideal Gas Law is working [B]AFTER[/B] the powder is burnt, please let us know. The law is only about 400yrs old, so maybe it hasn't been fully investigated and is actually incorrect:rolleyes:. Enlighten us with the calibers you are reloading with slow powders and short barrels. Let us know how it is working for you. If the powder is all burnt, why are you loosing speed? Wouldn't fast and slow powders work the same, regardless of which powder you use in a short barrel? You can't have it both ways, either the powder is burnt and should all work the same, or it isn't burnt and that is why you are loosing velocity (and this argument :D) Unless, you agree with #1 on my previous post. If this is the case, then let us know. You never responded to my question, trying to clarify your position. Thanks, AJ [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Barrel length and powder burn rates?
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