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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Custom action pressure ceiling.
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<blockquote data-quote="Pdvdh" data-source="post: 375225" data-attributes="member: 4191"><p>The brass is always the weak link, even with Lapua or RWS brass. </p><p></p><p>I am familiar with, and have read, the articles that document some pretty high pressures once case head swelling is measurable. Again not saying the brass is a means of quantifying the specific operating pressure of a given load - 62,000 psi versus 67,000 psi versus 73,000 psi. But repetitive loading of a single brass casing while working up a load will result in the trashing of the casing under repeated firings, and if one increments up cautiously, this brass casing will fail way before the rifle will. The brass case head and primer pocket will swell and become disfunctional before the rifle is damaged. </p><p></p><p>Therefore monitoring the condition of the brass should keep one from launching the bolt back through the skull - or even setting the bolt lugs back into the receiver. This is not as straight forward as "ABC - Doe Rae Me". Some would certainly be better off not reloading any cartridges, even to pre-established load data. Seriously. Others, with both the patience, understanding, and experience with reading over-pressure signs on brass casings and primers can develop a safe load with very little load data for a wildcat cartridge. </p><p></p><p>Heck, the safest thing of all is don't ever shoot a rifle, even with factory loads, because sometimes they'll blow primers too. </p><p></p><p>So for the newly initiated (probably not any of the members that have posted in this thread), again the methodology and idea is, once the brass is being taken out in short order with high pressure reloads then back off the powder charge until you're getting good brass life. The whole point is once those excessive loads are identified, reduce the powder charge to a safer level. Not to replace the spent brass with new casings and then continue to powder (and power) up time and time again, throwing away the spent brass after single shot usage. </p><p></p><p>I've measured case head expansion on all different brands of brass, Lapua, RWS, Winchester, Federal, Remington. Lapua and RWS will take a beating, but they will also expand case heads. It occurs in concert with the primer pocket swelling in each and every case I've experienced it. The guideline I've read and experienced is 0.0005" swelling of the case head <strong>with one firing</strong> is excessive pressure. Yeah there will be studies demonstrating that measured load pressures when the case head swells 0.0005" exceed SAAMI standards. Fair enough. The rifle didn't blow up & wasn't damaged. [Are there <strong>any</strong> studies that show a competent rifle ever let loose with less than 0.0005" case head expansion from one single case firing? Of course if the action or chamber explodes, the case head expands and may never be found - but you get the point.] Now... reduce the powder charge to whatever point you'd like. Almost every production rifle sold is seriously overpressured before it's ever released for sale. I know my Beretta Tikka T3 came new from the factory with gas etching of the bolt face caused from a pressure test load that let gas escape all around the edge of the primer. A perfect circle. For those that haven't seen this before, with new brass cases, this means the case head expanded until the primer blew it's seal in a single firing. Beretta didn't throw the rifle away. They sold it to me.</p><p></p><p>QuickLoad is a tool that was mentioned earlier and it certainly appears to give pretty good estimates of cartridge operating pressures. I don't own it or use it, but I've seen enough QuickLoad predicted load data and compared it to my reloading experiences to say it comes pretty darn close to estimating resultant cartridge/powder charge/bullet weight combination maximum loads & operating pressures.</p><p></p><p>If full blown pressure tested load data is available, use it. If there isn't, find a cartridge of the same caliber and capacity and use it as a guideline for both the optimum powders, as well as the approximate powder charges. If you wake up one morning and all load data is lost, you're the last one on earth, and you still have your eyesight, primers, cases, powder, bullets, and a means of weighing powder charges, then monitor brass cases and primers for signs of excessive pressure. Do so with a measure of caution and you should die of some cause other than 'rifle bolt through the brain'. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p>Oh... almost forgot. </p><p></p><p>There is one better way to establish a maximum working load for a <em>complete</em>, never before dreamed of, wildcat cartridge. Have your buddy build up the same cartridge and work the loads up in his rifle - first. <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></blockquote><p></p>
[QUOTE="Pdvdh, post: 375225, member: 4191"] The brass is always the weak link, even with Lapua or RWS brass. I am familiar with, and have read, the articles that document some pretty high pressures once case head swelling is measurable. Again not saying the brass is a means of quantifying the specific operating pressure of a given load - 62,000 psi versus 67,000 psi versus 73,000 psi. But repetitive loading of a single brass casing while working up a load will result in the trashing of the casing under repeated firings, and if one increments up cautiously, this brass casing will fail way before the rifle will. The brass case head and primer pocket will swell and become disfunctional before the rifle is damaged. Therefore monitoring the condition of the brass should keep one from launching the bolt back through the skull - or even setting the bolt lugs back into the receiver. This is not as straight forward as "ABC - Doe Rae Me". Some would certainly be better off not reloading any cartridges, even to pre-established load data. Seriously. Others, with both the patience, understanding, and experience with reading over-pressure signs on brass casings and primers can develop a safe load with very little load data for a wildcat cartridge. Heck, the safest thing of all is don't ever shoot a rifle, even with factory loads, because sometimes they'll blow primers too. So for the newly initiated (probably not any of the members that have posted in this thread), again the methodology and idea is, once the brass is being taken out in short order with high pressure reloads then back off the powder charge until you're getting good brass life. The whole point is once those excessive loads are identified, reduce the powder charge to a safer level. Not to replace the spent brass with new casings and then continue to powder (and power) up time and time again, throwing away the spent brass after single shot usage. I've measured case head expansion on all different brands of brass, Lapua, RWS, Winchester, Federal, Remington. Lapua and RWS will take a beating, but they will also expand case heads. It occurs in concert with the primer pocket swelling in each and every case I've experienced it. The guideline I've read and experienced is 0.0005" swelling of the case head [B]with one firing[/B] is excessive pressure. Yeah there will be studies demonstrating that measured load pressures when the case head swells 0.0005" exceed SAAMI standards. Fair enough. The rifle didn't blow up & wasn't damaged. [Are there [B]any[/B] studies that show a competent rifle ever let loose with less than 0.0005" case head expansion from one single case firing? Of course if the action or chamber explodes, the case head expands and may never be found - but you get the point.] Now... reduce the powder charge to whatever point you'd like. Almost every production rifle sold is seriously overpressured before it's ever released for sale. I know my Beretta Tikka T3 came new from the factory with gas etching of the bolt face caused from a pressure test load that let gas escape all around the edge of the primer. A perfect circle. For those that haven't seen this before, with new brass cases, this means the case head expanded until the primer blew it's seal in a single firing. Beretta didn't throw the rifle away. They sold it to me. QuickLoad is a tool that was mentioned earlier and it certainly appears to give pretty good estimates of cartridge operating pressures. I don't own it or use it, but I've seen enough QuickLoad predicted load data and compared it to my reloading experiences to say it comes pretty darn close to estimating resultant cartridge/powder charge/bullet weight combination maximum loads & operating pressures. If full blown pressure tested load data is available, use it. If there isn't, find a cartridge of the same caliber and capacity and use it as a guideline for both the optimum powders, as well as the approximate powder charges. If you wake up one morning and all load data is lost, you're the last one on earth, and you still have your eyesight, primers, cases, powder, bullets, and a means of weighing powder charges, then monitor brass cases and primers for signs of excessive pressure. Do so with a measure of caution and you should die of some cause other than 'rifle bolt through the brain'. :) Oh... almost forgot. There is one better way to establish a maximum working load for a [I]complete[/I], never before dreamed of, wildcat cartridge. Have your buddy build up the same cartridge and work the loads up in his rifle - first. :D [/QUOTE]
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