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Old May 31, 2000, 12:30 PM   #1
Steve Smith
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Join Date: December 9, 1999
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John Linebaugh and others say that the "typical" pressure signs don't always show up on straight walled large bore cases. He's personally fired .45 Colts over 50,000 cup and not had flattened or cratered primers. I should E-mail him, but I'd bet he's pretty busy. As I'm about to start loading for my Casull, I'd like to know how these large calibers express overpressure charges, since they might not display is by regular means. The Casull uses small rifle primers for more case strength, and that would leave less srea for pressure to affect the primer. Hmm...
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Old May 31, 2000, 12:39 PM   #2
Mal H
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Measuring the case diameter at the web (just above the rim) before/after firing is your best method. Any increase, no matter how small, could be a high pressure sign.
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Old May 31, 2000, 05:24 PM   #3
Hueco
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Measuring the web diameter is the ONLY reliable 100% sure way to detect high or over pressure. Primers are used a lot, but the cratering that sometimes occurs can have to do with the rifle, not the load. Use the web diameter.


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Old June 1, 2000, 01:09 PM   #4
bk40
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Measure the web diameter. Use once fired brass for taking measurements. If possible, I'd recommend firing factory loaded ammo and then pull several bullets from unfired factory ammo, seat the same bullet to same depth and crimp as factory, and see how much the factory load expands. Use that as your baseline. Web expansion over 0.0003" should be considered to hot. (You will need a micrometer)

One important thing to remember. Measuring casehead expansion is not an absolute measure of excessive pressure. Stay within published data and good luck.
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Old June 1, 2000, 06:18 PM   #5
Steve Smith
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Wow! Thanks a lot, guys!
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