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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="steve smith" data-source="post: 287232" data-attributes="member: 110"><p>OK Su37, Lets go back to high school chemistry class.</p><p></p><p>So lets take 5grams of fuel and 5 grams of O2, initiate combustion. The end result is you will have 10grams of gasses. So with smokeless powder the fuel and O2 are tied together in a chemical bond that is broken and then rearranged, resulting in the release of energy in the form of heat and the conversion of the solid to gas. </p><p></p><p>State 1- solid fuel+oxy (atmospheric O2 doesn't have any effect)</p><p>State 2- combustion products in the form of gasses (with solid residue being negligible).</p><p></p><p>Now for all intended purposes, the density of the gasses (whether from single base or double base, slow or fast burn rate) is identical. So, from this we can infer that whatever powder your using each powder will produce the exact same volume of gasses grain for grain. 5 grains of powder will produce 5grains of gasses at a volume of .xxx m^3.</p><p></p><p>So, from that we see that the only way to keep a load of 52gr of powder A (Ramshot Enforcer) and a load of 102.5gr of powder B (WC-872) , at the same maximum pressure is to slow the rate of deflagration. Both powders being double base ball powders in an extreme comparison in my 270-300Rum using the same bullet, pushed to max pressures.</p><p></p><p>Now, if we take powder A, your assertion that all the powder has completed combustion by the time the projectile has moved a few inches in the barrel could be correct, but in the case of powder B your assertion would make allmost 2x the amount of gas fit into virtually the same volume as in the case with powder A, yet still only have the same pressure. This simply cannot happen!</p><p></p><p>Now, your statement about "The gas created keeps expanding" is correct, but unless someone has been able to slow the rate at which gasses expand without the pressure going thru the roof, this is not what's going on. At least not entirely. What is happening is the rate of gas generation is much slower. In other words combustion with powder B continues long after combustion of powder A has completed. Now when I say "long after", it's really only about a ms, but when your talking bullets traveling down the barrel it's the difference between combustion completing at 2" vs 30".</p><p></p><p>Now then, If you don't believe that or don't understand it, then like before I suggest you go take a chemistry class and more especially a thermodynamics class. I promise you that it would really open up your eyes up to what wives tales you believe to be fact.</p></blockquote><p></p>
[QUOTE="steve smith, post: 287232, member: 110"] OK Su37, Lets go back to high school chemistry class. So lets take 5grams of fuel and 5 grams of O2, initiate combustion. The end result is you will have 10grams of gasses. So with smokeless powder the fuel and O2 are tied together in a chemical bond that is broken and then rearranged, resulting in the release of energy in the form of heat and the conversion of the solid to gas. State 1- solid fuel+oxy (atmospheric O2 doesn't have any effect) State 2- combustion products in the form of gasses (with solid residue being negligible). Now for all intended purposes, the density of the gasses (whether from single base or double base, slow or fast burn rate) is identical. So, from this we can infer that whatever powder your using each powder will produce the exact same volume of gasses grain for grain. 5 grains of powder will produce 5grains of gasses at a volume of .xxx m^3. So, from that we see that the only way to keep a load of 52gr of powder A (Ramshot Enforcer) and a load of 102.5gr of powder B (WC-872) , at the same maximum pressure is to slow the rate of deflagration. Both powders being double base ball powders in an extreme comparison in my 270-300Rum using the same bullet, pushed to max pressures. Now, if we take powder A, your assertion that all the powder has completed combustion by the time the projectile has moved a few inches in the barrel could be correct, but in the case of powder B your assertion would make allmost 2x the amount of gas fit into virtually the same volume as in the case with powder A, yet still only have the same pressure. This simply cannot happen! Now, your statement about "The gas created keeps expanding" is correct, but unless someone has been able to slow the rate at which gasses expand without the pressure going thru the roof, this is not what's going on. At least not entirely. What is happening is the rate of gas generation is much slower. In other words combustion with powder B continues long after combustion of powder A has completed. Now when I say "long after", it's really only about a ms, but when your talking bullets traveling down the barrel it's the difference between combustion completing at 2" vs 30". Now then, If you don't believe that or don't understand it, then like before I suggest you go take a chemistry class and more especially a thermodynamics class. I promise you that it would really open up your eyes up to what wives tales you believe to be fact. [/QUOTE]
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Barrel length and powder burn rates?
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