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Rifles, Reloading, Optics, Equipment
Reloading
Overpressure Signs ?
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<blockquote data-quote="Clark" data-source="post: 952183" data-attributes="member: 6600"><p>P.O. Ackley "Volume I Handbook for Shooters & Reloaders" 1962 Quotes Vernon Speer on page 148 and 149:</p><p></p><p>"There is a tremendous difference in the way different rifles handle pressure and it is entirely possible that a rifle used in one test was different in this respect than another one we used. We do not have a pressure gun in our laboratory, because it is in my opinion, backed up by quite a few years experience, as well as firing data from various laboratories pressure guns that data received from them is exceedingly unreliable. For a company such as Remington or Winchester having the same gun and operator comparable results to check on production problems are no doubt sufficiently accurate for the purpose for which they are used.</p><p></p><p>We use the head expansion method in determining the pressure at which a cartridge case was fired. It is our belief that the cartridge is the weakest link in the modern bolt action rifle. If the pressures at which the cartridge cases are fired do not exceed the elastic limit of the unsupported rim of the cartridge case, then we consider that the pressures are entirely usable, regardless of what they might be. We fire increased loads, increasing the charge at about a grain at time, checking the rim diameter of the cartridge case with sensitive measuring instruments, both before and after firing. If any measurable increase in the diameter of the rim of the case is noted, we consider that pressure excessive and reduce the charge about 6% and list it as a maximum load in our loading table. There is no reason why the handloader cannot use this same procedure himself and determine whether or not the loads he is using are safe and practical for use in his rifle.</p><p></p><p>In our laboratory we look for all signs of pressure such as sticky cases, tough extraction, flattened or cratered primers, as well as the rim expansion method noted above. Some cartridge cases are softer than others, notably Norma cases, and will not stand the higher pressure loadings possible in Remington and Winchester cases. This tends to bear out our contention that as long as the brass cartridge case is worked within the elastic range of the brass, then the pressure in the pounds per square inch, whatever it might be, is safe and practical for use in that particular cartridge. I hope I have been able to explain this pressure problem to your satisfaction.</p><p></p><p>Vernon D. Speer, February 6, 1958"</p></blockquote><p></p>
[QUOTE="Clark, post: 952183, member: 6600"] P.O. Ackley "Volume I Handbook for Shooters & Reloaders" 1962 Quotes Vernon Speer on page 148 and 149: "There is a tremendous difference in the way different rifles handle pressure and it is entirely possible that a rifle used in one test was different in this respect than another one we used. We do not have a pressure gun in our laboratory, because it is in my opinion, backed up by quite a few years experience, as well as firing data from various laboratories pressure guns that data received from them is exceedingly unreliable. For a company such as Remington or Winchester having the same gun and operator comparable results to check on production problems are no doubt sufficiently accurate for the purpose for which they are used. We use the head expansion method in determining the pressure at which a cartridge case was fired. It is our belief that the cartridge is the weakest link in the modern bolt action rifle. If the pressures at which the cartridge cases are fired do not exceed the elastic limit of the unsupported rim of the cartridge case, then we consider that the pressures are entirely usable, regardless of what they might be. We fire increased loads, increasing the charge at about a grain at time, checking the rim diameter of the cartridge case with sensitive measuring instruments, both before and after firing. If any measurable increase in the diameter of the rim of the case is noted, we consider that pressure excessive and reduce the charge about 6% and list it as a maximum load in our loading table. There is no reason why the handloader cannot use this same procedure himself and determine whether or not the loads he is using are safe and practical for use in his rifle. In our laboratory we look for all signs of pressure such as sticky cases, tough extraction, flattened or cratered primers, as well as the rim expansion method noted above. Some cartridge cases are softer than others, notably Norma cases, and will not stand the higher pressure loadings possible in Remington and Winchester cases. This tends to bear out our contention that as long as the brass cartridge case is worked within the elastic range of the brass, then the pressure in the pounds per square inch, whatever it might be, is safe and practical for use in that particular cartridge. I hope I have been able to explain this pressure problem to your satisfaction. Vernon D. Speer, February 6, 1958" [/QUOTE]
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