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Rifles, Reloading, Optics, Equipment
Reloading
must I full length size new brass?
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<blockquote data-quote="Bart B" data-source="post: 566690" data-attributes="member: 5302"><p>I've shot 15-round test groups with 30 caliber belted mag's at 1000 yards with brand new and properly done full length sized brass that equal or best current benchrest records. No brass prep was done to primer pockets, flash holes or neck walls but the new case necks were chamfered then resized with a standard full length die for uniform bullet tension.</p><p></p><p>The most accurate belted case rifles I know of all performed that well with either new or full length sized brass using the right type of dies. I'm referring to the size of the largest group fired in tests, not the smallest. The largest group fired is what one can count on all the time. The smallest groups only happen about 5% of the time and are the worst ones to judge accuracy with.</p><p></p><p>Backing off a standard full length sizing die to neck size is a popular technique But it usually forces the fired case shoulder forward causing a tight fit of the case in the chamber. And that makes the bolt close in different places for each shot; especially if the bolt face ain't squared up with the chamber axis. Sierra Bullets tried this fired case sizing method (as well as neck only sizing) in the early 1950's when developing reloading techniques for their cases used to test their products for accuracy; it didn't work. They got best accuracy properly full length sizing their cases. Sierra still does using Redding full bushing dies for cartridges the bushing dies are made for and conventional full length sizing dies for cartridges that don't. However, if one sets a fired case shoulder back too far with a standard full length sizing die, backing the die out a full turn may produce better results; expecially with rimless cases.</p></blockquote><p></p>
[QUOTE="Bart B, post: 566690, member: 5302"] I've shot 15-round test groups with 30 caliber belted mag's at 1000 yards with brand new and properly done full length sized brass that equal or best current benchrest records. No brass prep was done to primer pockets, flash holes or neck walls but the new case necks were chamfered then resized with a standard full length die for uniform bullet tension. The most accurate belted case rifles I know of all performed that well with either new or full length sized brass using the right type of dies. I'm referring to the size of the largest group fired in tests, not the smallest. The largest group fired is what one can count on all the time. The smallest groups only happen about 5% of the time and are the worst ones to judge accuracy with. Backing off a standard full length sizing die to neck size is a popular technique But it usually forces the fired case shoulder forward causing a tight fit of the case in the chamber. And that makes the bolt close in different places for each shot; especially if the bolt face ain't squared up with the chamber axis. Sierra Bullets tried this fired case sizing method (as well as neck only sizing) in the early 1950's when developing reloading techniques for their cases used to test their products for accuracy; it didn't work. They got best accuracy properly full length sizing their cases. Sierra still does using Redding full bushing dies for cartridges the bushing dies are made for and conventional full length sizing dies for cartridges that don't. However, if one sets a fired case shoulder back too far with a standard full length sizing die, backing the die out a full turn may produce better results; expecially with rimless cases. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
must I full length size new brass?
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