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Rifles, Reloading, Optics, Equipment
Reloading
Run-out help needed
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<blockquote data-quote="Bart B" data-source="post: 737259" data-attributes="member: 5302"><p>When I first started reloading .308 Win. and 26 or 30 caliber belted magnum cases, I used standard full length sizing and seating dies. Got bullet runout measured the traditional way (case resting in front of extractor groove and shoulder or neck, bullet in front of the neck or at the bullet tip) and got bullet runout readings up to 7 or 8 thousandths.</p><p></p><p>Then someone suggested I lap the necks out of those sizing dies to about 2 thousandths smaller than a loaded round's neck diameter. Using the same standard bullet seater, runout measured the same ways got better; up to 5 to 6 thousandths.</p><p></p><p>And finally, someone else suggested I change the way I chamfered my trimmed case mouths. Use a No. 4 or 5 screw extractor turned clockwise instead of the traditional deburring tool in case mouths. It puts a better angle on it. Then run those trimmed and deburred cases over a bore brush spinning in an electric drill. Using the same standard bullet seater, runout measured the same ways got better; up to 3 thousandths or a tiny bit more. And no more bullet jacked scraped off by that sharp, ragged edge left by traditional case mouth deburring tools. No difference in accuracy between rounds with zero runout compared to those with 3 thousandths.</p><p></p><p>Tried a few different chamber/micrometer type bullet seaters (Wilson, RCBS, Bonanza and a few others I now forget). No improvement over the standard one as far as runout's concerned. But the RCBS competition chamber type is sure a lot faster.</p><p></p><p>One thing that helps get bullets in loaded rounds well centered in the chamber throat and leade is having the case neck well centered on rimless bottleneck cases. That's the centering point on such cases when they're fired. If the case neck's not centered on the case shoulder, it won't be well aligned with the bore when it fires. And full length bushing dies do so better than neck only sizing dies. Guess that's why so many winning benchresters have moved away from neck only sizing to full length sizing with bushing dies (no expander ball) over the past several years.</p><p></p><p>Regarding how a loaded round's case neck fits the chamber neck. . . . . A .243 Win. round will perfectly center its neck and bullet in a .358 Win's chamber and bore when the round fires. Same for a .25-06 round in a .30-06 chamber.</p></blockquote><p></p>
[QUOTE="Bart B, post: 737259, member: 5302"] When I first started reloading .308 Win. and 26 or 30 caliber belted magnum cases, I used standard full length sizing and seating dies. Got bullet runout measured the traditional way (case resting in front of extractor groove and shoulder or neck, bullet in front of the neck or at the bullet tip) and got bullet runout readings up to 7 or 8 thousandths. Then someone suggested I lap the necks out of those sizing dies to about 2 thousandths smaller than a loaded round's neck diameter. Using the same standard bullet seater, runout measured the same ways got better; up to 5 to 6 thousandths. And finally, someone else suggested I change the way I chamfered my trimmed case mouths. Use a No. 4 or 5 screw extractor turned clockwise instead of the traditional deburring tool in case mouths. It puts a better angle on it. Then run those trimmed and deburred cases over a bore brush spinning in an electric drill. Using the same standard bullet seater, runout measured the same ways got better; up to 3 thousandths or a tiny bit more. And no more bullet jacked scraped off by that sharp, ragged edge left by traditional case mouth deburring tools. No difference in accuracy between rounds with zero runout compared to those with 3 thousandths. Tried a few different chamber/micrometer type bullet seaters (Wilson, RCBS, Bonanza and a few others I now forget). No improvement over the standard one as far as runout's concerned. But the RCBS competition chamber type is sure a lot faster. One thing that helps get bullets in loaded rounds well centered in the chamber throat and leade is having the case neck well centered on rimless bottleneck cases. That's the centering point on such cases when they're fired. If the case neck's not centered on the case shoulder, it won't be well aligned with the bore when it fires. And full length bushing dies do so better than neck only sizing dies. Guess that's why so many winning benchresters have moved away from neck only sizing to full length sizing with bushing dies (no expander ball) over the past several years. Regarding how a loaded round's case neck fits the chamber neck. . . . . A .243 Win. round will perfectly center its neck and bullet in a .358 Win's chamber and bore when the round fires. Same for a .25-06 round in a .30-06 chamber. [/QUOTE]
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