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Rifles, Reloading, Optics, Equipment
Reloading
sizing die help
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<blockquote data-quote="Bart B" data-source="post: 827721" data-attributes="member: 5302"><p>Sierra Bullets has got best accuracy by full length sizing all their cases used to shoot their bullets for quality control. Same for load development in factory rifles shooting their bullets. They've been doing it since the 1950's.</p><p></p><p>Best results are with dies whose neck diameter is a couple thousandths smaller than a loaded round's neck (no expander ball used) and its sized all the way back to the shoulder. The fired case body is sized down a bit and the fired case shoulder's set back a thousandth or two. If this ain't done correctly, then such full length sized cases may well not shoot as well as neck only sized ones; expecially when the fired case shoulder's set back way too far.</p><p></p><p>Note that bottleneck cases headspacing on their shoulders center perfectly in the chamber when fired regardless of how much clearance there is between the case body and neck to the chamber in those areas. It's the case shoulder that centers the case up front in the chamber shoulder, not the body or neck. Case necks float clear of the chamber neck regardless of clearance and are very well centered there if they're well centered on the case shoulder. Case body's are clear of the chamber wall except for its back end at the pressure ring where the extractor pushes it against the chamber at that point. </p><p></p><p>Neck only sizing dies do not center case necks on case shoulders as well as full length sizing dies do. This is why most benchresters now full length size their fired cases, but only a minimal amount. Their smallest groups didn't get any smaller but their largest ones sure did.</p></blockquote><p></p>
[QUOTE="Bart B, post: 827721, member: 5302"] Sierra Bullets has got best accuracy by full length sizing all their cases used to shoot their bullets for quality control. Same for load development in factory rifles shooting their bullets. They've been doing it since the 1950's. Best results are with dies whose neck diameter is a couple thousandths smaller than a loaded round's neck (no expander ball used) and its sized all the way back to the shoulder. The fired case body is sized down a bit and the fired case shoulder's set back a thousandth or two. If this ain't done correctly, then such full length sized cases may well not shoot as well as neck only sized ones; expecially when the fired case shoulder's set back way too far. Note that bottleneck cases headspacing on their shoulders center perfectly in the chamber when fired regardless of how much clearance there is between the case body and neck to the chamber in those areas. It's the case shoulder that centers the case up front in the chamber shoulder, not the body or neck. Case necks float clear of the chamber neck regardless of clearance and are very well centered there if they're well centered on the case shoulder. Case body's are clear of the chamber wall except for its back end at the pressure ring where the extractor pushes it against the chamber at that point. Neck only sizing dies do not center case necks on case shoulders as well as full length sizing dies do. This is why most benchresters now full length size their fired cases, but only a minimal amount. Their smallest groups didn't get any smaller but their largest ones sure did. [/QUOTE]
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sizing die help
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