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Rifles, Reloading, Optics, Equipment
Reloading
Increased case capacity, decreased velocity?
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<blockquote data-quote="Michael Eichele" data-source="post: 245396" data-attributes="member: 1007"><p>In a very tight chamber a case may not expand enough to "add" any significant volume. </p><p></p><p>In most factory rifles, chambers are cut very large. When you fire a round the factory spec'd case is now the size of the chamber. YES this isncreases the volume. Yes this (all else being equal) will cause a slight decrease of pressure AND velocity. If neck sizing only a slight increase of powder will be needed to get the load back to normal velocities. How slight depends on the case capacity AND burn rate of the load/powder combo. This is where chronographs are your best friend.</p><p></p><p>Now, seating the bullet further out is another story. Yes seating the bullet out farther will increase volume but getting the bullet closer to the lands INCREASES pressure AND velocity. They may cancel eachother out TO A POINT, but sooner or later (most likely sooner) the pressure will increase dramatically as the bullet gets closer to the lands. It all depends on how much freebore you are starting with and how tempermental the power in question is.</p><p></p><p>Clear as mud?</p><p></p><p>If in doubt, leave the seating depth alone.</p></blockquote><p></p>
[QUOTE="Michael Eichele, post: 245396, member: 1007"] In a very tight chamber a case may not expand enough to "add" any significant volume. In most factory rifles, chambers are cut very large. When you fire a round the factory spec'd case is now the size of the chamber. YES this isncreases the volume. Yes this (all else being equal) will cause a slight decrease of pressure AND velocity. If neck sizing only a slight increase of powder will be needed to get the load back to normal velocities. How slight depends on the case capacity AND burn rate of the load/powder combo. This is where chronographs are your best friend. Now, seating the bullet further out is another story. Yes seating the bullet out farther will increase volume but getting the bullet closer to the lands INCREASES pressure AND velocity. They may cancel eachother out TO A POINT, but sooner or later (most likely sooner) the pressure will increase dramatically as the bullet gets closer to the lands. It all depends on how much freebore you are starting with and how tempermental the power in question is. Clear as mud? If in doubt, leave the seating depth alone. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Increased case capacity, decreased velocity?
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