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Rifles, Reloading, Optics, Equipment
Reloading
Minimum .308 Charges?
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<blockquote data-quote="Bart B" data-source="post: 114376" data-attributes="member: 5302"><p>Whatever powder you use, I'd be sure it's enough to have pressure high enough that the fired case doesn't end up with shorter headspace than before. Such cases may not be safe to fire again as they would have excessive headspace.</p><p></p><p>If the fired primer's backed out any amount, that's evidence the charge weight wasn't enough to expand the case to fill the chamber. The firing pin drives the case hard against the chamber shoulder with enough force to set the case shoulder back .001-inch or more. Low pressure from reduced loads won't be enough to push the back fourth of the case body back against the bolt while the front part's pressed hard against the chamber wall. Reloading such cases once or twice may result in head separation. And that's a dangerous thing. I've used .308 Win. reduced loads with 38 grains of IMR4084 behind a 168 in new cases and the primer was backed out about .010-in but 40 grains was enough to keep it flush with the case head. These once fired cases had too much excessive headspace to reload even in a full-length sizing die as their shoulder wouldn't move forward enough.</p><p></p><p>Many folks don't believe this will happen with rimless bottleneck cases but it does. Use a case headspace gage (Stoney Point, RCBS Precision Mic, others) to measure case headspace before priming a fired case, prime it then fire that primed empty case in the chamber. Measure that case headspace then repeat this. You'll see case headspace will get shorter each time a primer's popped in it.</p><p></p><p>If you need to load greatly reduced powder charges to get the low velocity desired, you may only reload cases once to do that.</p></blockquote><p></p>
[QUOTE="Bart B, post: 114376, member: 5302"] Whatever powder you use, I'd be sure it's enough to have pressure high enough that the fired case doesn't end up with shorter headspace than before. Such cases may not be safe to fire again as they would have excessive headspace. If the fired primer's backed out any amount, that's evidence the charge weight wasn't enough to expand the case to fill the chamber. The firing pin drives the case hard against the chamber shoulder with enough force to set the case shoulder back .001-inch or more. Low pressure from reduced loads won't be enough to push the back fourth of the case body back against the bolt while the front part's pressed hard against the chamber wall. Reloading such cases once or twice may result in head separation. And that's a dangerous thing. I've used .308 Win. reduced loads with 38 grains of IMR4084 behind a 168 in new cases and the primer was backed out about .010-in but 40 grains was enough to keep it flush with the case head. These once fired cases had too much excessive headspace to reload even in a full-length sizing die as their shoulder wouldn't move forward enough. Many folks don't believe this will happen with rimless bottleneck cases but it does. Use a case headspace gage (Stoney Point, RCBS Precision Mic, others) to measure case headspace before priming a fired case, prime it then fire that primed empty case in the chamber. Measure that case headspace then repeat this. You'll see case headspace will get shorter each time a primer's popped in it. If you need to load greatly reduced powder charges to get the low velocity desired, you may only reload cases once to do that. [/QUOTE]
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Minimum .308 Charges?
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