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Rifles, Reloading, Optics, Equipment
Reloading
Full length sizing VS neck sizing
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<blockquote data-quote="Mikecr" data-source="post: 2566824" data-attributes="member: 1521"><p>I've never seen that happen. Necks spring back to clear chamber neck without leaving any interference.</p><p></p><p>The reason I surmise relates to pressure applied to area and neck thickness per that area.</p><p>A 60Kpsi pressure produces less force against neck area -vs- case body area. There is more barrel steel around chamber necks, so chamber neck expands less. The relative thickness of necks for area is high, so necks have no problem springing back to clear.</p><p></p><p>You can run out of clearance at the neck-shoulder junction from donut brass thickness -if seating bullet bearing deep enough to push it out. But sizing won't fix that. You can run out of rechambering clearance if necks are over annealed, but that alone won't stop you from rechambering, nor hurt anything at all.</p><p></p><p>The biggest issue I have with FL sizing of necks is that it creates huge neck tension variances.</p><p>If bullet bearing is not seated fully through necks but you FL sized the neck, then you leave a non expanded portion of neck to bind against bullet bearing-base junction. This will raise SD, mess with tune, and unless neck friction is very high, CBTO will change over time (similar as with compressed loads). FL sizing of necks also brings donut brass thickness into tension, and that brass thickness is less controlled/less consistent. Fl sizing of necks raises neck tension considerably (excessively), and higher of anything means higher variance of it. FL sizing of necks raises runout, and finally, by FL sizing of necks you give up a valuable adjustment to neck tension (sizing length).</p><p></p><p>The only occasion where FL sizing of necks could benefit is with small underbore cartridges (competitive) that need very high starting pressure to reach extreme peak pressure levels. In this case nobody cares about the variance in tension, they just need it high enough.</p><p>That is a special situation that does not apply to hunting capacity cartridges, which really are viably limited to SAAMI max pressures..</p></blockquote><p></p>
[QUOTE="Mikecr, post: 2566824, member: 1521"] I've never seen that happen. Necks spring back to clear chamber neck without leaving any interference. The reason I surmise relates to pressure applied to area and neck thickness per that area. A 60Kpsi pressure produces less force against neck area -vs- case body area. There is more barrel steel around chamber necks, so chamber neck expands less. The relative thickness of necks for area is high, so necks have no problem springing back to clear. You can run out of clearance at the neck-shoulder junction from donut brass thickness -if seating bullet bearing deep enough to push it out. But sizing won't fix that. You can run out of rechambering clearance if necks are over annealed, but that alone won't stop you from rechambering, nor hurt anything at all. The biggest issue I have with FL sizing of necks is that it creates huge neck tension variances. If bullet bearing is not seated fully through necks but you FL sized the neck, then you leave a non expanded portion of neck to bind against bullet bearing-base junction. This will raise SD, mess with tune, and unless neck friction is very high, CBTO will change over time (similar as with compressed loads). FL sizing of necks also brings donut brass thickness into tension, and that brass thickness is less controlled/less consistent. Fl sizing of necks raises neck tension considerably (excessively), and higher of anything means higher variance of it. FL sizing of necks raises runout, and finally, by FL sizing of necks you give up a valuable adjustment to neck tension (sizing length). The only occasion where FL sizing of necks could benefit is with small underbore cartridges (competitive) that need very high starting pressure to reach extreme peak pressure levels. In this case nobody cares about the variance in tension, they just need it high enough. That is a special situation that does not apply to hunting capacity cartridges, which really are viably limited to SAAMI max pressures.. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Full length sizing VS neck sizing
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