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Rifles, Reloading, Optics, Equipment
AR15/10 Rifles
Mystery spiral on 223 bullet?
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<blockquote data-quote="Pdvdh" data-source="post: 1291288" data-attributes="member: 4191"><p>Interesting. </p><p>My AR doesn't spin the cartridge like that at all. My opinion is that yours doesn't either. I'll explain the basis for my position. I'm on no mission to make my conclusions your conclusions.</p><p></p><p>Within the past 12 months I've worked on my AR several times. I examined my fired cases, and also examined unfired cartridges that had been chambered.</p><p>The first corrective measure I took was in response to noting that the bottom front of my bolt was cutting a scratch into the top shell casing left in the mag while ramming the cartridges home into the chamber. So I rounded and polished the sharp leading edge from the bottom of the bolt and that cured the scarring of the sidewalls of the cases.</p><p></p><p>Later I noticed a spiral scratch on my bullets when I extracted a live round from the chamber. The spiral scar was similar to the twist on a barber shop post or a candy cane. An elongated spiral, with about 10-15 degrees of rotation. Investigation determined this was being caused by the bolt lug recesses in both of the two feed slots in the breech. The scars were substantial, cutting a sharp spiral with a raised lip. Enough to affect bullet BC and perhaps accuracy. So I used a Dremel hone to round off the sharp 90* edges and that eliminated 95% of the depth of these scratches.</p><p></p><p>The point being, my cartridges were not rotating more than ~ 15*, based on the scratch pattern the bolt lug recesses left on my bullets. I also researched the bullet scratching I saw on my bullets and learned this was fairly common. Never once did I read of cartridges being rotated even 90*, let alone 720* or more. Yours aren't either, in my opinion.</p><p></p><p>The angle of the spiral scratch on my bullets was less than the angle of the cam pin slot cut into the bolt. So a bit less than 15*, in my estimation. The scars left on the bullets were about 1/3" long. 10-15 degree rotation. Identical to the photos others posted showing bolt lug recess scars on their bullets.</p><p></p><p>I doubt your cartridges are being rotated 1-2 revolutions by the bolt slamming them home. I'd have to it on high speed photography to believe otherwise. </p><p></p><p>If you Google research this, I don't think you'll find evidence of multiple cartridge revolutions during chambering. I know I didn't. And I used search terms that should have snagged some hits.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1291288, member: 4191"] Interesting. My AR doesn't spin the cartridge like that at all. My opinion is that yours doesn't either. I'll explain the basis for my position. I'm on no mission to make my conclusions your conclusions. Within the past 12 months I've worked on my AR several times. I examined my fired cases, and also examined unfired cartridges that had been chambered. The first corrective measure I took was in response to noting that the bottom front of my bolt was cutting a scratch into the top shell casing left in the mag while ramming the cartridges home into the chamber. So I rounded and polished the sharp leading edge from the bottom of the bolt and that cured the scarring of the sidewalls of the cases. Later I noticed a spiral scratch on my bullets when I extracted a live round from the chamber. The spiral scar was similar to the twist on a barber shop post or a candy cane. An elongated spiral, with about 10-15 degrees of rotation. Investigation determined this was being caused by the bolt lug recesses in both of the two feed slots in the breech. The scars were substantial, cutting a sharp spiral with a raised lip. Enough to affect bullet BC and perhaps accuracy. So I used a Dremel hone to round off the sharp 90* edges and that eliminated 95% of the depth of these scratches. The point being, my cartridges were not rotating more than ~ 15*, based on the scratch pattern the bolt lug recesses left on my bullets. I also researched the bullet scratching I saw on my bullets and learned this was fairly common. Never once did I read of cartridges being rotated even 90*, let alone 720* or more. Yours aren't either, in my opinion. The angle of the spiral scratch on my bullets was less than the angle of the cam pin slot cut into the bolt. So a bit less than 15*, in my estimation. The scars left on the bullets were about 1/3" long. 10-15 degree rotation. Identical to the photos others posted showing bolt lug recess scars on their bullets. I doubt your cartridges are being rotated 1-2 revolutions by the bolt slamming them home. I'd have to it on high speed photography to believe otherwise. If you Google research this, I don't think you'll find evidence of multiple cartridge revolutions during chambering. I know I didn't. And I used search terms that should have snagged some hits. [/QUOTE]
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AR15/10 Rifles
Mystery spiral on 223 bullet?
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