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Rifles, Reloading, Optics, Equipment
Reloading
I need help with pressure problems
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<blockquote data-quote="Mikecr" data-source="post: 649593" data-attributes="member: 1521"><p>Yawn extractors and ejectors are different things, applying differently, to different casehead areas.</p><p>All I see in the pic is ejector marks, possibly caused by a weak ejector spring combined with excess headspace. This, given no other pressure signs.</p><p>I don't see any extractor marks, or flow. By the time you actually get extractor flow, you'd have a bunch of other signs as well.</p><p></p><p>AtownBcat</p><p>'Near the webs' by my definition is first NOT casehead expansion(CHE), or pressure ring expansion(PRE) points as horribly defined in the past. These stemmed from hopeless attempts to define actual pressure in the field. But because of the gamut of cartridge designs and situation variances, there is no defining of actual pressure via cartridge measurements alone.</p><p>I measure at a point forward of the webs that would represent the tangency(seamless transition) of web thickness to body thickness in a new case.</p><p>This is often also the point of thinning(a ring) with stretching cases. It can be seen as a line from dull brass above to shiny below. What's happening here to form that visible line in the sand is thicker web brass not expanding as much as body brass. So you have a point that represents the very widest point on the body as fireformed.</p><p></p><p>After I've fireformed cases(while determining best bullet seating), and before working up loads, I do a pressure test across a chrono & calibrate my QuickLoad file for the cartridge/barrel. I do this to find MY MAX, which I'll never go past again, and I let QL tell me what that pressure is based on the velocity-vs-load.</p><p>MY MAX is MY PROBLEM pressure, and is the point where extraction is sticky from well designed/fireformed/non-FL sized cases. This is typically calculated as ~57-65Kpsi, which is at or near SAAMI max, which is lower than some run, but high enough for me. I get no other pressure signs with this, and it holds from powder to powder provided my QL powder files are calibrated to lot.</p><p></p><p>For this testing I use simple calipers slid down the body to widest point. I don't mess with a blade mic & set datum because the actual datum(webline) can change from case to case. Also 0.0005 in resolution is good enough for the test.</p><p>As I go up in charge, I'll see the webline grow and settle at some point through several increases. This is where brass is expanding to the expanded chamber, and then springing back more than the chamber is springing back(allowing easy extraction). As I continue to go up in charge I will eventually measure a step change(from settled) of .0005. This represents brass yielding that is no longer allowing it's springback to clear the chamber. Sticky extraction, MY MAX..</p><p>This has held as valuable test criteria so far from 223 to WSSM.</p><p></p><p>So given that your extraction is not sticky, and having no other real pressure signs, and running known reduced loads, you do not have a pressure problem, or a brass problem.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 649593, member: 1521"] Yawn extractors and ejectors are different things, applying differently, to different casehead areas. All I see in the pic is ejector marks, possibly caused by a weak ejector spring combined with excess headspace. This, given no other pressure signs. I don't see any extractor marks, or flow. By the time you actually get extractor flow, you'd have a bunch of other signs as well. AtownBcat 'Near the webs' by my definition is first NOT casehead expansion(CHE), or pressure ring expansion(PRE) points as horribly defined in the past. These stemmed from hopeless attempts to define actual pressure in the field. But because of the gamut of cartridge designs and situation variances, there is no defining of actual pressure via cartridge measurements alone. I measure at a point forward of the webs that would represent the tangency(seamless transition) of web thickness to body thickness in a new case. This is often also the point of thinning(a ring) with stretching cases. It can be seen as a line from dull brass above to shiny below. What's happening here to form that visible line in the sand is thicker web brass not expanding as much as body brass. So you have a point that represents the very widest point on the body as fireformed. After I've fireformed cases(while determining best bullet seating), and before working up loads, I do a pressure test across a chrono & calibrate my QuickLoad file for the cartridge/barrel. I do this to find MY MAX, which I'll never go past again, and I let QL tell me what that pressure is based on the velocity-vs-load. MY MAX is MY PROBLEM pressure, and is the point where extraction is sticky from well designed/fireformed/non-FL sized cases. This is typically calculated as ~57-65Kpsi, which is at or near SAAMI max, which is lower than some run, but high enough for me. I get no other pressure signs with this, and it holds from powder to powder provided my QL powder files are calibrated to lot. For this testing I use simple calipers slid down the body to widest point. I don't mess with a blade mic & set datum because the actual datum(webline) can change from case to case. Also 0.0005 in resolution is good enough for the test. As I go up in charge, I'll see the webline grow and settle at some point through several increases. This is where brass is expanding to the expanded chamber, and then springing back more than the chamber is springing back(allowing easy extraction). As I continue to go up in charge I will eventually measure a step change(from settled) of .0005. This represents brass yielding that is no longer allowing it's springback to clear the chamber. Sticky extraction, MY MAX.. This has held as valuable test criteria so far from 223 to WSSM. So given that your extraction is not sticky, and having no other real pressure signs, and running known reduced loads, you do not have a pressure problem, or a brass problem. [/QUOTE]
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I need help with pressure problems
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