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Rifles, Reloading, Optics, Equipment
Reloading
Let's talk about the "dreaded donut"
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<blockquote data-quote="rscott5028" data-source="post: 485617" data-attributes="member: 24624"><p>I'll respond just to keep the discussion going because I'd like to learn more. But, I don't have a lot of experience with this issue. So, here's my understanding and hopefully, one of the more knowledgeable will correct me....</p><p> </p><p>The so-called "doughnut" forms on the inside of your case at the intersection of the shoulder and neck. In essence, it's simply a thickening of the brass at that point. </p><p> </p><p>While it may occur during resizing operations to some extent, I think it mostly develops during firing. Due to outward pressure in the chamber, brass flows forward during the firing process and cases stretch and become thinner each time. </p><p> </p><p>As brass flows from the body into the shoulder, the chamber itself (or sizing die) forces the brass to turn the corner inward/down towards the neck. But, when it flows from the shoulder to the neck, there is no solid barrier on the inside of the case to force the brass to turn the corner cleanly towards the neck/chamber. </p><p> </p><p>It mostly turns that corner because of the cohesive properties of a maleable solid. But, some build up/thickening occurs on the inside of the case neck at that intersection with the shoulder. </p><p> </p><p>Many of us are never aware this is happening because it's not enough to prevent the bullet from seating and because our press/expander are not particularly sensitive. But if you use pin gauges, you will find the doughnut after some number of firings. </p><p> </p><p>It's simple enough to ignore and probably isn't going to bother a guy that shoots MOA at 100 yds. But, it affects bullet seating and evenness of your neck tension which are increasingly important as we strive for consistency and precision. </p><p> </p><p>How do we prevent the doughnut? You can't. It occurs regardless of upsizing, downsizing, or using factory cartridges. Having invited argument by saying that, I think the magnitude of the issue is less with necking down and even less again with factory cases/cartridges. </p><p> </p><p>You can exacerbate the problem by necking up which causes necks to thicken. And whether you neck up or not, when you neck turn your cases, leaving a sharp edge where a clean radius previously existed between the shoulder and neck may encourage the doughnut. </p><p> </p><p>As such, a neck turning tool with a perferctly ground radius on the end may help alleviate the issue. But, the real solution is simply to monitor for the presence of the doughnut and to remove/ream it with a fluted cutter pilot tool. </p><p> </p><p>Again, that's my limited opinion. But, I'm eager for someone to help me get it straight. </p><p> </p><p>thanks!</p><p>richard</p></blockquote><p></p>
[QUOTE="rscott5028, post: 485617, member: 24624"] I'll respond just to keep the discussion going because I'd like to learn more. But, I don't have a lot of experience with this issue. So, here's my understanding and hopefully, one of the more knowledgeable will correct me.... The so-called "doughnut" forms on the inside of your case at the intersection of the shoulder and neck. In essence, it's simply a thickening of the brass at that point. While it may occur during resizing operations to some extent, I think it mostly develops during firing. Due to outward pressure in the chamber, brass flows forward during the firing process and cases stretch and become thinner each time. As brass flows from the body into the shoulder, the chamber itself (or sizing die) forces the brass to turn the corner inward/down towards the neck. But, when it flows from the shoulder to the neck, there is no solid barrier on the inside of the case to force the brass to turn the corner cleanly towards the neck/chamber. It mostly turns that corner because of the cohesive properties of a maleable solid. But, some build up/thickening occurs on the inside of the case neck at that intersection with the shoulder. Many of us are never aware this is happening because it's not enough to prevent the bullet from seating and because our press/expander are not particularly sensitive. But if you use pin gauges, you will find the doughnut after some number of firings. It's simple enough to ignore and probably isn't going to bother a guy that shoots MOA at 100 yds. But, it affects bullet seating and evenness of your neck tension which are increasingly important as we strive for consistency and precision. How do we prevent the doughnut? You can't. It occurs regardless of upsizing, downsizing, or using factory cartridges. Having invited argument by saying that, I think the magnitude of the issue is less with necking down and even less again with factory cases/cartridges. You can exacerbate the problem by necking up which causes necks to thicken. And whether you neck up or not, when you neck turn your cases, leaving a sharp edge where a clean radius previously existed between the shoulder and neck may encourage the doughnut. As such, a neck turning tool with a perferctly ground radius on the end may help alleviate the issue. But, the real solution is simply to monitor for the presence of the doughnut and to remove/ream it with a fluted cutter pilot tool. Again, that's my limited opinion. But, I'm eager for someone to help me get it straight. thanks! richard [/QUOTE]
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Reloading
Let's talk about the "dreaded donut"
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