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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
RL33 Temperature Regression Thread
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<blockquote data-quote="Pdvdh" data-source="post: 993133" data-attributes="member: 4191"><p>Hi Jeff,</p><p>It doesn't increase pressure generated inside the cartridge. The water on the cartridge case or inside the chamber acts as a lubricant to reduce the friction between the brass casing and the steel chamber. That friction does provide some reduction in the force that the case head exerts on the face of the bolt when the cartridge is fired. If the chamber wall or cartridge case is lubricated with water or oil, or ice, or anything else that reduces the coefficient of friction between the brass casing and the steel chamber wall, the resistance to case head setback against the bolt face is reduced, and the case head does thrust against the bolt face with higher force. Which will produce the same symptoms and indications that would be observed with a dry chamber and cartridge when the cartridge has been loaded to higher/excessive pressures. </p><p></p><p>Your observations of signs of increased pressure are correct and I have observed them myself. <strong>bigngreen </strong>brought this to my attention years ago, so I lubricated the exterior of some .280 AI cartridges and fired them, just to see what happened. And I did experience indications of increased pressure, just as if I'd added 2 grains of powder and fired the cartridge in a dry chamber.</p><p></p><p>However these indications/symptom of increased pressure are just that. They are not increased pressures. Only symptoms of increased pressure. They're caused by increased force applied by the case head against the bolt face, caused not by higher internal case pressure, but by a reduction in the friction between the brass casing and rifle chamber.</p><p></p><p>If we didn't commonly run our loads up to and over maximum book pressures in order to improve MW, we wouldn't experience this. We stop just shy of pressure indications with a dry chamber, and then the slight increase in case head to bolt face force created with a lubricated chamber presents all the symptoms of excessive pressure. The pressure is no more excessive than the pressure we load to all of the time with a dry chamber.</p><p></p><p>Hope this makes sense. I'm pretty darn confident in this explanation.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 993133, member: 4191"] Hi Jeff, It doesn't increase pressure generated inside the cartridge. The water on the cartridge case or inside the chamber acts as a lubricant to reduce the friction between the brass casing and the steel chamber. That friction does provide some reduction in the force that the case head exerts on the face of the bolt when the cartridge is fired. If the chamber wall or cartridge case is lubricated with water or oil, or ice, or anything else that reduces the coefficient of friction between the brass casing and the steel chamber wall, the resistance to case head setback against the bolt face is reduced, and the case head does thrust against the bolt face with higher force. Which will produce the same symptoms and indications that would be observed with a dry chamber and cartridge when the cartridge has been loaded to higher/excessive pressures. Your observations of signs of increased pressure are correct and I have observed them myself. [B]bigngreen [/B]brought this to my attention years ago, so I lubricated the exterior of some .280 AI cartridges and fired them, just to see what happened. And I did experience indications of increased pressure, just as if I'd added 2 grains of powder and fired the cartridge in a dry chamber. However these indications/symptom of increased pressure are just that. They are not increased pressures. Only symptoms of increased pressure. They're caused by increased force applied by the case head against the bolt face, caused not by higher internal case pressure, but by a reduction in the friction between the brass casing and rifle chamber. If we didn't commonly run our loads up to and over maximum book pressures in order to improve MW, we wouldn't experience this. We stop just shy of pressure indications with a dry chamber, and then the slight increase in case head to bolt face force created with a lubricated chamber presents all the symptoms of excessive pressure. The pressure is no more excessive than the pressure we load to all of the time with a dry chamber. Hope this makes sense. I'm pretty darn confident in this explanation. [/QUOTE]
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RL33 Temperature Regression Thread
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