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Rifles, Reloading, Optics, Equipment
Reloading
rookie dealing with possible pressure signs
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<blockquote data-quote="Bart B" data-source="post: 566328" data-attributes="member: 5302"><p>This doesn't make sense to me at all.</p><p></p><p>If headspace is changed to make it longer/greater, peak pressure will go down for a given load. If it's made shorter/smaller (setting the barrel back?), peak pressure will go up. But a few thousandths either way will not make any significant difference in peak pressure.</p><p></p><p>Note that that rimless bottleneck case is driven full forward in the chamber seating its shoulder hard against the chamber shoulder when the round fires. And the case shoulder stays hard against the chamber shoulder while the round fires. As the case expands from pressure buildup, its shoulder slides on the chamber shoulder sucking shoulder and neck brass back as the case body stretches back until the case head stops against the bolt face. This ends up making the case length shorter after firing.</p><p></p><p>By the looks of the case in the picture, there may have been a lube dimple in it before it was fired and peak pressure wasn't eough to flatten it out against the chamber wall. Your load may have been very much reduced.</p></blockquote><p></p>
[QUOTE="Bart B, post: 566328, member: 5302"] This doesn't make sense to me at all. If headspace is changed to make it longer/greater, peak pressure will go down for a given load. If it's made shorter/smaller (setting the barrel back?), peak pressure will go up. But a few thousandths either way will not make any significant difference in peak pressure. Note that that rimless bottleneck case is driven full forward in the chamber seating its shoulder hard against the chamber shoulder when the round fires. And the case shoulder stays hard against the chamber shoulder while the round fires. As the case expands from pressure buildup, its shoulder slides on the chamber shoulder sucking shoulder and neck brass back as the case body stretches back until the case head stops against the bolt face. This ends up making the case length shorter after firing. By the looks of the case in the picture, there may have been a lube dimple in it before it was fired and peak pressure wasn't eough to flatten it out against the chamber wall. Your load may have been very much reduced. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
rookie dealing with possible pressure signs
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