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Hunting
Long Range Hunting & Shooting
Belted vs. non-belted for accuracy.
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<blockquote data-quote="johnnyk" data-source="post: 301494" data-attributes="member: 307"><p>You're not wrong at all AJ. The "speculation" or "theory" behind the non-belted cartridges being more accurate, was that to establish standards for measuring and maintaining headspace, a dimension is specified between the bolt face and a reference point, called the "datum line". For rimless, semi-rimmed and rebated cartridges (.284 family), the datum line is established at a point on the shoulder. For non-belted cases this is roughly half-way the shoulder where it rest against the chamber. The datum line for belted magnums is the forward edge of the recess provided for the belt.</p><p> I guess they (nay-sayers) figured that since the belted mag cases headspace off the recess in the chamber that the front end (bullet end) just flops around up there in the forward part of the chamber.</p><p> This "problem", as it's perceived, can be overcome with a properly adjusted die. To do this, unscrew the die a full turn and run a smutted, fire-formed case into the die chamber. You should be able to detect a mark where the case neck stopped inside the die neck cavity. Screw the die back down until the die shoulder is in firm contact against the case shoulder. Reload a couple of "dummy" rounds and chamer them in your rifle. You should be able to feel a slight pressure caused by contact of the shoulder. Wa-La, now you have a belted magnum case headspacing the same as the "more accurate" non-bleted. Hope this helps. JohnnyK.</p></blockquote><p></p>
[QUOTE="johnnyk, post: 301494, member: 307"] You're not wrong at all AJ. The "speculation" or "theory" behind the non-belted cartridges being more accurate, was that to establish standards for measuring and maintaining headspace, a dimension is specified between the bolt face and a reference point, called the "datum line". For rimless, semi-rimmed and rebated cartridges (.284 family), the datum line is established at a point on the shoulder. For non-belted cases this is roughly half-way the shoulder where it rest against the chamber. The datum line for belted magnums is the forward edge of the recess provided for the belt. I guess they (nay-sayers) figured that since the belted mag cases headspace off the recess in the chamber that the front end (bullet end) just flops around up there in the forward part of the chamber. This "problem", as it's perceived, can be overcome with a properly adjusted die. To do this, unscrew the die a full turn and run a smutted, fire-formed case into the die chamber. You should be able to detect a mark where the case neck stopped inside the die neck cavity. Screw the die back down until the die shoulder is in firm contact against the case shoulder. Reload a couple of "dummy" rounds and chamer them in your rifle. You should be able to feel a slight pressure caused by contact of the shoulder. Wa-La, now you have a belted magnum case headspacing the same as the "more accurate" non-bleted. Hope this helps. JohnnyK. [/QUOTE]
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Belted vs. non-belted for accuracy.
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