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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
7mm Rem. Mag vs 300 Win. Mag
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<blockquote data-quote="Clark" data-source="post: 1068815" data-attributes="member: 6600"><p>Feenix,</p><p>When I run the numbers on 7mmRM 180 Berger 2900 fps [with H1000] I get 58,604 psi</p><p>When I run the numbers on 300WM 215 Berger 3050 fps [with H4381sc] I get 77,877 psi</p><p></p><p>In terms of QL psi and belted magnums, if I work up until there is the smallest amount of extractor groove growth, a more accurate pre cursor to loose primer pockets, and then back off 4% powder charge for margin, then check it with QL, I get 74,000 psi with any belted magnum.</p><p></p><p>With temp stable powders like the Hodgdon extreme series or Allinant ARcomp, I use 4% derating.</p><p>Most powders are 6%.</p><p>Re17 is even more.</p><p></p><p>You know you are operating QL correctly when belted mag extractor groove growth minus 4% powder calculates at 74kpsi, and the velocity prediction is in the middle of the chrono string. Some jugs of powder are different than the QL library and require compensation. Jamming into the lands requires changing the start pressure. Hitting the pressure and velocity with QL takes a little practice, but it is easier than hitting targets at long range.</p></blockquote><p></p>
[QUOTE="Clark, post: 1068815, member: 6600"] Feenix, When I run the numbers on 7mmRM 180 Berger 2900 fps [with H1000] I get 58,604 psi When I run the numbers on 300WM 215 Berger 3050 fps [with H4381sc] I get 77,877 psi In terms of QL psi and belted magnums, if I work up until there is the smallest amount of extractor groove growth, a more accurate pre cursor to loose primer pockets, and then back off 4% powder charge for margin, then check it with QL, I get 74,000 psi with any belted magnum. With temp stable powders like the Hodgdon extreme series or Allinant ARcomp, I use 4% derating. Most powders are 6%. Re17 is even more. You know you are operating QL correctly when belted mag extractor groove growth minus 4% powder calculates at 74kpsi, and the velocity prediction is in the middle of the chrono string. Some jugs of powder are different than the QL library and require compensation. Jamming into the lands requires changing the start pressure. Hitting the pressure and velocity with QL takes a little practice, but it is easier than hitting targets at long range. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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7mm Rem. Mag vs 300 Win. Mag
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