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Rifles, Reloading, Optics, Equipment
Reloading
Let's talk about the "dreaded donut"
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<blockquote data-quote="boomtube" data-source="post: 486605" data-attributes="member: 9215"><p>Mikecr is correct. </p><p> </p><p>At least a PROPERLY resized case expands in diameter when fired and will often - usually? - get a tad shorter. Then, when it gets squeezed down in an FL die it will get 'squished' longer. The extra length can only go to the neck so it gets longer during sizing. That extra length comes from the case body as part of the wall moves to the shoulder while part of the shoulder moves to the neck and that creates, or may eventually create, a 'donut.'</p><p> </p><p>Yes, IF a case is much shorter than the chamber, a really sloppy fit in other words, it will stretch just above the web during firing but that will not happen IF the case is properly FLsized, (or simply neck sized) for a snug chamber fit. That chamber slop and resulting stretching happens due to over-enthusastic FL sizing. Such repeated stretching may evenually case a head seperation and, possibly, a donut too. But, <u>none of that happens because the brass "flows" under the pressure of firing as if it were putty</u>; it isn't.</p><p> </p><p>Reforming/sizing a case down to a smaller caliber, such as going from .308 to .243, puts what was neck wall into the shoulder and no donut will be formed. On the other hand, reforming up, a .243 to a .308, will put what had been shoulder brass into the neck and that IS the donut.</p><p> </p><p>Reaming will remove the donut but reaming does nothing otherwise to the neck, if it was non-concentric to start with a reamer leaves it that way. I prefer to neck turn instead (I like the same Forster HOT-100 hand held neck turner as Woods uses), but using the turner requires that the donut be forced to the outside first. Annealing, followed by a Lyman M expander die usually does the turning preparation work for me.</p><p> </p><p>Most of the BR donuts come from up-sizing .220 Russian to 6mm PPC. If we reform a .308/.243 to .22-250 or .30-06/.35 Whelen to .243, a part of the original case side wall becomes neck and we will get a huge donut, but not many of us do such massive case refoming as that! <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /></p></blockquote><p></p>
[QUOTE="boomtube, post: 486605, member: 9215"] Mikecr is correct. At least a PROPERLY resized case expands in diameter when fired and will often - usually? - get a tad shorter. Then, when it gets squeezed down in an FL die it will get 'squished' longer. The extra length can only go to the neck so it gets longer during sizing. That extra length comes from the case body as part of the wall moves to the shoulder while part of the shoulder moves to the neck and that creates, or may eventually create, a 'donut.' Yes, IF a case is much shorter than the chamber, a really sloppy fit in other words, it will stretch just above the web during firing but that will not happen IF the case is properly FLsized, (or simply neck sized) for a snug chamber fit. That chamber slop and resulting stretching happens due to over-enthusastic FL sizing. Such repeated stretching may evenually case a head seperation and, possibly, a donut too. But, [U]none of that happens because the brass "flows" under the pressure of firing as if it were putty[/U]; it isn't. Reforming/sizing a case down to a smaller caliber, such as going from .308 to .243, puts what was neck wall into the shoulder and no donut will be formed. On the other hand, reforming up, a .243 to a .308, will put what had been shoulder brass into the neck and that IS the donut. Reaming will remove the donut but reaming does nothing otherwise to the neck, if it was non-concentric to start with a reamer leaves it that way. I prefer to neck turn instead (I like the same Forster HOT-100 hand held neck turner as Woods uses), but using the turner requires that the donut be forced to the outside first. Annealing, followed by a Lyman M expander die usually does the turning preparation work for me. Most of the BR donuts come from up-sizing .220 Russian to 6mm PPC. If we reform a .308/.243 to .22-250 or .30-06/.35 Whelen to .243, a part of the original case side wall becomes neck and we will get a huge donut, but not many of us do such massive case refoming as that! :D [/QUOTE]
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Let's talk about the "dreaded donut"
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