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Rifles, Reloading, Optics, Equipment
Reloading
Why can’t we get good dies!
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<blockquote data-quote="Mikecr" data-source="post: 2209077" data-attributes="member: 1521"><p>Yeah, pressure ring is probably the same as my redneck web line.</p><p>I run the test with NEW cases that I've culled out of lot for thickness variances(but same overall thickness). </p><p>Just going up & up in charges until I reach a point where FL sizing would be required immediately. </p><p>A point I call MyMax. Don't know what else to call it.</p><p>Again, that's a single firing of new brass, with my local stuff. And it's not fire formed brass.</p><p></p><p>I use a blade mic w/base & shims (but calipers also work) to measure growth at the pressure ring. As I go up from minimum I'll see up to around 1thou steady growth, then plateau, and at some point several charges higher I'll see a step change of another ~1/2thou (runaway). So far I've found the plateau breaks into that runaway on passing SAAMI max, per QuickLoad.</p><p>The last plateau charge is logged as MyMax, which I'll stay under during load development and any future changes(per QL pressure est.). This example is with typical chamber clearances from new brass dimension of around 2thou near webs.</p><p></p><p>As consistent as this has worked out for me, I have to wonder if the folks at SAAMI do the same. </p><p>With new brass, but in an instrumented test barrel.</p><p>Maybe common knowledge, I just don't know. I never did this test to determine pressure, and I don't really care about what the pressures are. Instead, what I care about are pressure 'problems', which I may run into during this testing (before MyMax).</p><p></p><p>The 'problem' I'm forcing here is where cases yield to plastic.</p><p>Brass has memory. It wants to go where it's been, and that makes sense when you consider grain structure breaking inside it. </p><p>Brass fired even once at MyMax will go right back there, on next firing, no matter the sizing plan. This is because you can never truly recover brass that's yielded(even with annealing). The puzzle pieces (grain structure) will never fit or grow the same again.</p><p></p><p>I actually learned this in a 7th grade reloading class (1976). The testing was demonstrated & discussed.</p><p>They probably don't teach reloading or even hunter safety in public schools anymore..</p></blockquote><p></p>
[QUOTE="Mikecr, post: 2209077, member: 1521"] Yeah, pressure ring is probably the same as my redneck web line. I run the test with NEW cases that I've culled out of lot for thickness variances(but same overall thickness). Just going up & up in charges until I reach a point where FL sizing would be required immediately. A point I call MyMax. Don't know what else to call it. Again, that's a single firing of new brass, with my local stuff. And it's not fire formed brass. I use a blade mic w/base & shims (but calipers also work) to measure growth at the pressure ring. As I go up from minimum I'll see up to around 1thou steady growth, then plateau, and at some point several charges higher I'll see a step change of another ~1/2thou (runaway). So far I've found the plateau breaks into that runaway on passing SAAMI max, per QuickLoad. The last plateau charge is logged as MyMax, which I'll stay under during load development and any future changes(per QL pressure est.). This example is with typical chamber clearances from new brass dimension of around 2thou near webs. As consistent as this has worked out for me, I have to wonder if the folks at SAAMI do the same. With new brass, but in an instrumented test barrel. Maybe common knowledge, I just don't know. I never did this test to determine pressure, and I don't really care about what the pressures are. Instead, what I care about are pressure 'problems', which I may run into during this testing (before MyMax). The 'problem' I'm forcing here is where cases yield to plastic. Brass has memory. It wants to go where it's been, and that makes sense when you consider grain structure breaking inside it. Brass fired even once at MyMax will go right back there, on next firing, no matter the sizing plan. This is because you can never truly recover brass that's yielded(even with annealing). The puzzle pieces (grain structure) will never fit or grow the same again. I actually learned this in a 7th grade reloading class (1976). The testing was demonstrated & discussed. They probably don't teach reloading or even hunter safety in public schools anymore.. [/QUOTE]
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Why can’t we get good dies!
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