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Extreme Long Range Hunting & Shooting (ELR)
My New Defensive Edge LRKM
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<blockquote data-quote="Fiftydriver" data-source="post: 844191" data-attributes="member: 10"><p>Broz,</p><p> </p><p>Have you guys ever used Norma brass with your current loads as a check for your pressures? The reason I ask is because when I was developing my 7mm AM, 300 AX and 338 AX, using the Lapua brass made it very difficult to read pressures. In the early days of the AMs and AXs, I was chambering them in modified Rem 700s and this made me a bit uncomfortable as I knew from load development that the Lapua case would take well over 70,000 psi and just smile and show no sign at all of high pressures.</p><p> </p><p>THis made me very nervous knowing that the rifles based on the Rem 700s would be going out and someone would be running the Lapua case to its limits and be WELL over what the Rem 700 should be subjected to long term.</p><p> </p><p>Now, this is not the concern with your project or any other custom receiver based project, I only bring this up because for me, when I was doing load development, I knew that I was unable to read any pressure sign on the Lapua case. As such, when doing load development, I only used Norma brass because while its very high quality, its also relatively soft compared to the Lapua brass. </p><p> </p><p>In my testing, a 338 Lapua with Norma brass will loosen its primer pockets at nearly exactly the same load and velocity as the Remington RUM brass when used in same barrel lengths with same bullets. The Rem RUM brass has been reported to have permanent case head deformation at around 65,000 psi. Which means simply the primer pockets start to expand at this pressure. So is the same for the Norma brass.</p><p> </p><p>Using this information, I was able to develop loads for my 7mm AM, 300 AX and 338 AX in the Norma cases and load them up to roughly the point where primer pockets would loosen to the point of not being usible in roughly 4 firings. With this load data, I knew that my wildcats were being loaded to roughly 65,000 psi. Then I could simply switch over to the Lapua brand brass and never see a single pressure sign EVER!!!</p><p> </p><p>Just curious if you or Shawn has done any testing in this manor to check the pressures your running at.</p><p> </p><p>I am not saying your running over 70K, just curious if you have done any pressure testing like this?</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 844191, member: 10"] Broz, Have you guys ever used Norma brass with your current loads as a check for your pressures? The reason I ask is because when I was developing my 7mm AM, 300 AX and 338 AX, using the Lapua brass made it very difficult to read pressures. In the early days of the AMs and AXs, I was chambering them in modified Rem 700s and this made me a bit uncomfortable as I knew from load development that the Lapua case would take well over 70,000 psi and just smile and show no sign at all of high pressures. THis made me very nervous knowing that the rifles based on the Rem 700s would be going out and someone would be running the Lapua case to its limits and be WELL over what the Rem 700 should be subjected to long term. Now, this is not the concern with your project or any other custom receiver based project, I only bring this up because for me, when I was doing load development, I knew that I was unable to read any pressure sign on the Lapua case. As such, when doing load development, I only used Norma brass because while its very high quality, its also relatively soft compared to the Lapua brass. In my testing, a 338 Lapua with Norma brass will loosen its primer pockets at nearly exactly the same load and velocity as the Remington RUM brass when used in same barrel lengths with same bullets. The Rem RUM brass has been reported to have permanent case head deformation at around 65,000 psi. Which means simply the primer pockets start to expand at this pressure. So is the same for the Norma brass. Using this information, I was able to develop loads for my 7mm AM, 300 AX and 338 AX in the Norma cases and load them up to roughly the point where primer pockets would loosen to the point of not being usible in roughly 4 firings. With this load data, I knew that my wildcats were being loaded to roughly 65,000 psi. Then I could simply switch over to the Lapua brand brass and never see a single pressure sign EVER!!! Just curious if you or Shawn has done any testing in this manor to check the pressures your running at. I am not saying your running over 70K, just curious if you have done any pressure testing like this? [/QUOTE]
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