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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Tight neck chamber
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<blockquote data-quote="Mikecr" data-source="post: 1095516" data-attributes="member: 1521"><p>Ultimately it's all about spring back, and wall thickness does directly affect this. So unless you hold a brass lot(all you'll need) of really uniform thickness, you should consider turning those within a reasonable thickness variance range(cull out the rest). This is where up front planning comes in.</p><p>Brass springs back counter to last sizing, most immediately, and more of the balance over time. This happens with necks, shoulders, body, and even your seated primers creep over time. </p><p>When you bushing downsize, the necks spring back outward away from that action(decreasing tension), and will continue over time. This may not be good for long term performance consistency, and the greater the sizing energy added, the greater the counter action -to a limit(~1.5thou).</p><p>You don't need to downsize so much that a mandrel(I use Sinclair's) would actually upsize, and you **** sure don't need to be upsizing necks with bullet seating.. Doing so will contribute to big seating depth variances, setup for big spring back variances(tension variances), and increase loaded runout. The mandrel is an intermediate step to relieve much of this(to reduce the amplitude of spring back energy/variance). The most consistent tension = the least tension = the least variances of it.</p><p>There are BR shooters who turn a shelf in the neck for seated bullet bases to rest against. A planned precision donut. They don't need any tension, and therefore mitigate tension variance.</p><p>Not practical for hunting, but fine for BR with bullets seated into the lands anyway.</p><p></p><p>The Sinclair mandrel system is by far the best. And you can get carbide mandrels for it from PMA(who I believe designed Sinclair's entire turning system).</p><p>I've installed a load cell in my expander die to measure force of pre-seating. This provides a more accurate relative tension indication than bullet seating force, as bullets are terrible expanders.</p><p>This is not actual tension(spring back gripping force), but useful,, another thread.</p><p>The sinclair turning/expander mandrels are also the correct size for reloading, where K&Ms are not.</p><p></p><p>Tight clearances do need well taken care of ammo and chambers. This will never be a problem for me, or for a long range hunter. My father taught me to respect guns, not only in safety and honorable possession, but in condition as well. </p><p>My guns are pristine.</p><p>As far as reloading, I control all local aspects of it. I measure and verify everything, always. I am not afraid of my abilities to do this, because it's habit to think about what I'm doing. </p><p>My ammo is perfect.</p><p></p><p>As far as other's notions and fears, I addressed this in post #26.</p><p>Whenever someone implies this or that without supporting understanding of it, be sure there are logical reasons. </p><p>The prize in it is not what they observed, but the reasons.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 1095516, member: 1521"] Ultimately it's all about spring back, and wall thickness does directly affect this. So unless you hold a brass lot(all you'll need) of really uniform thickness, you should consider turning those within a reasonable thickness variance range(cull out the rest). This is where up front planning comes in. Brass springs back counter to last sizing, most immediately, and more of the balance over time. This happens with necks, shoulders, body, and even your seated primers creep over time. When you bushing downsize, the necks spring back outward away from that action(decreasing tension), and will continue over time. This may not be good for long term performance consistency, and the greater the sizing energy added, the greater the counter action -to a limit(~1.5thou). You don't need to downsize so much that a mandrel(I use Sinclair's) would actually upsize, and you **** sure don't need to be upsizing necks with bullet seating.. Doing so will contribute to big seating depth variances, setup for big spring back variances(tension variances), and increase loaded runout. The mandrel is an intermediate step to relieve much of this(to reduce the amplitude of spring back energy/variance). The most consistent tension = the least tension = the least variances of it. There are BR shooters who turn a shelf in the neck for seated bullet bases to rest against. A planned precision donut. They don't need any tension, and therefore mitigate tension variance. Not practical for hunting, but fine for BR with bullets seated into the lands anyway. The Sinclair mandrel system is by far the best. And you can get carbide mandrels for it from PMA(who I believe designed Sinclair's entire turning system). I've installed a load cell in my expander die to measure force of pre-seating. This provides a more accurate relative tension indication than bullet seating force, as bullets are terrible expanders. This is not actual tension(spring back gripping force), but useful,, another thread. The sinclair turning/expander mandrels are also the correct size for reloading, where K&Ms are not. Tight clearances do need well taken care of ammo and chambers. This will never be a problem for me, or for a long range hunter. My father taught me to respect guns, not only in safety and honorable possession, but in condition as well. My guns are pristine. As far as reloading, I control all local aspects of it. I measure and verify everything, always. I am not afraid of my abilities to do this, because it's habit to think about what I'm doing. My ammo is perfect. As far as other's notions and fears, I addressed this in post #26. Whenever someone implies this or that without supporting understanding of it, be sure there are logical reasons. The prize in it is not what they observed, but the reasons. [/QUOTE]
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