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Rifles, Reloading, Optics, Equipment
Reloading
Help me determine what is causing my runout!
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<blockquote data-quote="boomtube" data-source="post: 303958" data-attributes="member: 9215"><p>"what is causing my runout!"</p><p> </p><p>Well, it's really hard to be sure from here but we can try.</p><p> </p><p>First, I wonder how long you have used the gage, and how you are using it and how you are intrepreting it.</p><p> </p><p>Taking the last first, maybe I can cut your runtout in half immediately. I can't imagine any case sent through a Reddiing (or Forster) seater can exit with .015" of real run out (RO). You do understand that what you see on the gage is called Total Indicated Runout (TIR) and that the actual RO is only half of TIR? </p><p> </p><p>No seater can correct for a bent neck. With the Sinclair tool, I think neck RO is taken near the mouth while the body supported at the base and just below the shoulder, right? So, RO mostly shows how much out of alignment the neck is to the centerline of the body. Very little of that RO comes from the seater, per se, so hopeful efforts to correct by seating part way, turning and completing seating isn't really going to do much good. </p><p> </p><p>Consider that if a neck were 1 1/2" long and you took one reading at the present location, then a second near the outer end, the second reading would be much greater simply because the angle of error shows more difference the further away from the start of the error it's read. The anglular error would be unchanged but the TIR would appear greater. Meaning, if we carefully push a bullet perfectly straight nto a slightly bent neck, the dial indicater will swing further when we measure off the tip simply because it's reading further out. If that's what you are seeing, understand that <u>the "real runout" remains only that of the bent neck </u>AND only half of the TIR, and it's due to the bent neck, not so much the seater. </p><p> </p><p>Most sizing dies and chambers are perfectly straight, or nearly so. But, pulling a largely unsupported expander out of a totally unsupported case neck almost guarantees the necks will be pulled out of perfect alignment, each time we size/expand them. All factory case necks have thicker:thinner sides. The thinner side will give way, stretching more than the thicker so the neck CL will tend to drift as the expander is withdrawn. </p><p> </p><p>Obviously any angular difference between the between the center lines of the inside diameter (ID) and outside diameter (OD) of a pipe/neck can't be corrected with a die. Nor is alignment likely to be correctable with a reamer. Reamers make the necks thinner but they tend to follow the existing hole while doing it. </p><p> </p><p>Concentricity out of the seating die requries that the inside, not the outside, of the neck be concentric and no conventional die can assure that. Correcting that requres outside neck turning as the best way to improve the neck ID and OD centerlines. </p><p> </p><p>That starts with obtainly the best possible necks before turning.</p><p>Obtaining a sized but still straight neck is best done with a Lee Collet Neck sizer die. I've also found the Lyman "M" die expander used with a stripped FL die to be a close second. That's because the M expander it pushes IN, instead of pulling OUT as conventional ball expander does. Neither is die is magic, they can't fully correct for all of the neck's error but using either is MUCH better than a conventional sizer/expander.</p><p> </p><p>When the inside of the necks are as straight as you can make them, turn the outside to (try) to make the outsides match the innerds. Turning neck for factory chambers has limited value, don't bother skinning off more than perhaps 70-80% of the circumference. The Forster Hand Operated Turner (HOT 100) is the least expensive, easy to use neck turner with a carbide cutter and micrometer type adjustment knob I know of. It's NOT "BR" grade but it is plenty good for factory chambers; try it.</p><p> </p><p>Conclusion; Concentricity requires good necks, good necks requires fairly good brass that's very well selected and prepped. All any good seater can add is to not destroy what the case prepping has done.</p><p> </p><p>Good luck!</p></blockquote><p></p>
[QUOTE="boomtube, post: 303958, member: 9215"] "what is causing my runout!" Well, it's really hard to be sure from here but we can try. First, I wonder how long you have used the gage, and how you are using it and how you are intrepreting it. Taking the last first, maybe I can cut your runtout in half immediately. I can't imagine any case sent through a Reddiing (or Forster) seater can exit with .015" of real run out (RO). You do understand that what you see on the gage is called Total Indicated Runout (TIR) and that the actual RO is only half of TIR? No seater can correct for a bent neck. With the Sinclair tool, I think neck RO is taken near the mouth while the body supported at the base and just below the shoulder, right? So, RO mostly shows how much out of alignment the neck is to the centerline of the body. Very little of that RO comes from the seater, per se, so hopeful efforts to correct by seating part way, turning and completing seating isn't really going to do much good. Consider that if a neck were 1 1/2" long and you took one reading at the present location, then a second near the outer end, the second reading would be much greater simply because the angle of error shows more difference the further away from the start of the error it's read. The anglular error would be unchanged but the TIR would appear greater. Meaning, if we carefully push a bullet perfectly straight nto a slightly bent neck, the dial indicater will swing further when we measure off the tip simply because it's reading further out. If that's what you are seeing, understand that [U]the "real runout" remains only that of the bent neck [/U]AND only half of the TIR, and it's due to the bent neck, not so much the seater. Most sizing dies and chambers are perfectly straight, or nearly so. But, pulling a largely unsupported expander out of a totally unsupported case neck almost guarantees the necks will be pulled out of perfect alignment, each time we size/expand them. All factory case necks have thicker:thinner sides. The thinner side will give way, stretching more than the thicker so the neck CL will tend to drift as the expander is withdrawn. Obviously any angular difference between the between the center lines of the inside diameter (ID) and outside diameter (OD) of a pipe/neck can't be corrected with a die. Nor is alignment likely to be correctable with a reamer. Reamers make the necks thinner but they tend to follow the existing hole while doing it. Concentricity out of the seating die requries that the inside, not the outside, of the neck be concentric and no conventional die can assure that. Correcting that requres outside neck turning as the best way to improve the neck ID and OD centerlines. That starts with obtainly the best possible necks before turning. Obtaining a sized but still straight neck is best done with a Lee Collet Neck sizer die. I've also found the Lyman "M" die expander used with a stripped FL die to be a close second. That's because the M expander it pushes IN, instead of pulling OUT as conventional ball expander does. Neither is die is magic, they can't fully correct for all of the neck's error but using either is MUCH better than a conventional sizer/expander. When the inside of the necks are as straight as you can make them, turn the outside to (try) to make the outsides match the innerds. Turning neck for factory chambers has limited value, don't bother skinning off more than perhaps 70-80% of the circumference. The Forster Hand Operated Turner (HOT 100) is the least expensive, easy to use neck turner with a carbide cutter and micrometer type adjustment knob I know of. It's NOT "BR" grade but it is plenty good for factory chambers; try it. Conclusion; Concentricity requires good necks, good necks requires fairly good brass that's very well selected and prepped. All any good seater can add is to not destroy what the case prepping has done. Good luck! [/QUOTE]
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