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Rifles, Reloading, Optics, Equipment
Reloading
Case/Bullet Run-out: How Big a Deal Is It?
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<blockquote data-quote="Mikecr" data-source="post: 355835" data-attributes="member: 1521"><p>Well as a simple example, a perfectly concentric cartridge might have thickness variance in it's neck(pushed outward) that could be measured or discarded as runout. </p><p>Concentricity is variance only from a centerline. So to see this case as actually concentric you would just move your indicator away from the known thickness variance(noise).</p><p>Also the case could be a complete banana and still be measured as concentric, if you pin both ends and indicate nearest one(often the bullet tip). </p><p>Doesn't make it straight of course, but it is 'centered' in measurement.</p><p></p><p>In a sense, if your bullets are jammed, your chamber is big & sloppy, and your boltface is square, concentric would work just fine. The ammo might actually rest centered in the chamber w/respect to the bore.</p><p>But concentric ammo could not even chamber in some of my barrels -unless it was also -straight-</p><p></p><p>When you look at an H&H, think of a jump rope. This concentricity gage sees only displacement of the rope's arc nearest one end(a pinned end). That's fine because it's not a runout gage. </p><p>Now look at a Sinclair. You note here that the center of the rope is pinned, and displacemnet of it's arc is indicated at a free end. This won't show the concentricity of the arc. But trust me, if you straighten that rope, it will be concentric.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 355835, member: 1521"] Well as a simple example, a perfectly concentric cartridge might have thickness variance in it's neck(pushed outward) that could be measured or discarded as runout. Concentricity is variance only from a centerline. So to see this case as actually concentric you would just move your indicator away from the known thickness variance(noise). Also the case could be a complete banana and still be measured as concentric, if you pin both ends and indicate nearest one(often the bullet tip). Doesn't make it straight of course, but it is 'centered' in measurement. In a sense, if your bullets are jammed, your chamber is big & sloppy, and your boltface is square, concentric would work just fine. The ammo might actually rest centered in the chamber w/respect to the bore. But concentric ammo could not even chamber in some of my barrels -unless it was also -straight- When you look at an H&H, think of a jump rope. This concentricity gage sees only displacement of the rope's arc nearest one end(a pinned end). That's fine because it's not a runout gage. Now look at a Sinclair. You note here that the center of the rope is pinned, and displacemnet of it's arc is indicated at a free end. This won't show the concentricity of the arc. But trust me, if you straighten that rope, it will be concentric. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Case/Bullet Run-out: How Big a Deal Is It?
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