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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
to ackley or not
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<blockquote data-quote="Fiftydriver" data-source="post: 588724" data-attributes="member: 10"><p>Just a bit more to add, when an AI chambering is set up properly, the virgin brass should have a slight (roughly 0.004-0.005") crush fit in the chamber. This means that the shoulder of the case where the shoulder/neck junction is will be crushed slightly when the virgin brass is chambered. This is critical, unfortunately, many AI rifles are not set up properly. </p><p> </p><p>You should be able to feel the crush fit of the brass when fireforming with just a bit of resistance on the bolt when you lock it down.</p><p> </p><p>This crush fit does a couple things, first, by design, its intended to hold the case solidly back againt the bolt face. This aids in good powder ignition which helps fireforming and improved round, it also nearly eliminates case wall stretching and thinning ahead of the solid case head and will prevent case head seperation. This is very important.</p><p> </p><p>This also helps center the fireforming round in the chamber properly which aids in accuracy. This is why a properly set up AI rifle will generally shoot ffireforming loads very well, often times into that 1/2 moa group class.</p><p> </p><p>On the Nosler brass that you were getting flattened primers, this was a headspace issue that was causing the flattened primers. If you want to use the Nosler brass, you should at minimum set the chamber up to headspace properly on this cases shoulder. IF your getting primer flattening, likely you also got some case stretching as well. May be very mild but may also be worth looking into. A case head seperation is not a fun thing at best and can be very serious at worse.</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 588724, member: 10"] Just a bit more to add, when an AI chambering is set up properly, the virgin brass should have a slight (roughly 0.004-0.005") crush fit in the chamber. This means that the shoulder of the case where the shoulder/neck junction is will be crushed slightly when the virgin brass is chambered. This is critical, unfortunately, many AI rifles are not set up properly. You should be able to feel the crush fit of the brass when fireforming with just a bit of resistance on the bolt when you lock it down. This crush fit does a couple things, first, by design, its intended to hold the case solidly back againt the bolt face. This aids in good powder ignition which helps fireforming and improved round, it also nearly eliminates case wall stretching and thinning ahead of the solid case head and will prevent case head seperation. This is very important. This also helps center the fireforming round in the chamber properly which aids in accuracy. This is why a properly set up AI rifle will generally shoot ffireforming loads very well, often times into that 1/2 moa group class. On the Nosler brass that you were getting flattened primers, this was a headspace issue that was causing the flattened primers. If you want to use the Nosler brass, you should at minimum set the chamber up to headspace properly on this cases shoulder. IF your getting primer flattening, likely you also got some case stretching as well. May be very mild but may also be worth looking into. A case head seperation is not a fun thing at best and can be very serious at worse. [/QUOTE]
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