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Rifles, Reloading, Optics, Equipment
Reloading
Quick load vs pressure signs
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<blockquote data-quote="Mikecr" data-source="post: 1504769" data-attributes="member: 1521"><p>This is often correlation without causation.</p><p>That is, 'Problems' occurring with increasing pressure may be pressure problems -but not problem pressures. </p><p>A really good example of this is with primer pockets loosening. By far most believe this is a symptom of problem pressures, and it can be. But it can also present with moderate pressure shooting of rat turds in a violin case.</p><p>Some folks can remove a problem assumed as pressure with bushing of their bolt for reduced firing pin clearance, or better control over their headspacing. They'll crack fewer cases with better matching of their sized cases to individual chamber. Many bolts are mistimed and extract with problem difficulty.</p><p></p><p>There is a way to test for and monitor 'local Max Pressure' as it manifests into problems for sizing & extraction. I call it 'MyMax', and it has nothing to do with published, predicted, or actual pressure. It is simply the point of case expansion where body sizing is required to rechamber the case. I measure it with a blade mic, ~.2-.25" up from the extraction groove, at a visual web-line. I do a new brass test, increasing incrementally in charge and plotting the web-line result. It will grow, level off, and then sharply take off (at MyMax). Yeah, you can FL size back down from here, but the primer pockets will loosen so fast as to have you constantly replacing cases. If not one of the more modern case designs, extraction will be difficult here, even with continued FL sizing.</p><p></p><p>QL, especially when calibrated, is about as good for pressure predicting as math provides. But never forget that this is PREDICTING, and not actual measure. Even with Pressure Trace/strain gauge measure, the results are still a loose correlation to test barrel values (which your barrel is not).</p><p>So none of us know what our pressures actually are.</p><p>Then again, it doesn't matter what our pressures actually are.</p><p>What matters are the LOCAL problems and how we associate them with OUR loads.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 1504769, member: 1521"] This is often correlation without causation. That is, 'Problems' occurring with increasing pressure may be pressure problems -but not problem pressures. A really good example of this is with primer pockets loosening. By far most believe this is a symptom of problem pressures, and it can be. But it can also present with moderate pressure shooting of rat turds in a violin case. Some folks can remove a problem assumed as pressure with bushing of their bolt for reduced firing pin clearance, or better control over their headspacing. They'll crack fewer cases with better matching of their sized cases to individual chamber. Many bolts are mistimed and extract with problem difficulty. There is a way to test for and monitor 'local Max Pressure' as it manifests into problems for sizing & extraction. I call it 'MyMax', and it has nothing to do with published, predicted, or actual pressure. It is simply the point of case expansion where body sizing is required to rechamber the case. I measure it with a blade mic, ~.2-.25" up from the extraction groove, at a visual web-line. I do a new brass test, increasing incrementally in charge and plotting the web-line result. It will grow, level off, and then sharply take off (at MyMax). Yeah, you can FL size back down from here, but the primer pockets will loosen so fast as to have you constantly replacing cases. If not one of the more modern case designs, extraction will be difficult here, even with continued FL sizing. QL, especially when calibrated, is about as good for pressure predicting as math provides. But never forget that this is PREDICTING, and not actual measure. Even with Pressure Trace/strain gauge measure, the results are still a loose correlation to test barrel values (which your barrel is not). So none of us know what our pressures actually are. Then again, it doesn't matter what our pressures actually are. What matters are the LOCAL problems and how we associate them with OUR loads. [/QUOTE]
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Quick load vs pressure signs
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