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Rifles, Reloading, Optics, Equipment
Reloading
280 AI Reloading Input
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<blockquote data-quote="cdherman" data-source="post: 1870773" data-attributes="member: 12282"><p>-- lots of questions to answer here. I'll try to give my thoughts....</p><p></p><p>** You have once and twice fired brass, but you didn't make it too clear if that brass was fired in your cooper or not. If you have acquired brass fired in a different gun, you MUST full length resize and start over with your gun. Neck sizing or just touching the the shoulder back is not an option. If the brass was fired in your gun, then you can try and just back the shoulder down by .002". But here's another problem -- if you are using the expander ball with a FL die and the neck is work hardened and/or the ball/neck is not well lubed, you will "pull" the shoulder back out. This could be happening to you. I personally measure my brass thickness, use bushing dies, and then use a final Sinclair mandrel to make the inside diameters identical. Its all about neck tension. Or so I have read and believe. You are correct to measure the shoulder at .375, as that bushing is what Hornady says to use in the 280 AI. BUT, if the expander ball is pulling the shoulder "out" closer to the neck, you will NOT detect that with the case comparator. You are measuring at .375. Not right next to the neck. Hope this is all making sense.</p><p></p><p>** You have several lengths of brass. The max length listed in my Hornady manual (and they state they are using SAAMI) is 2.590". Trim to length is 2.530. Your measured length of 2.560" seems "short", but regardless, you are no where close to the real dangerous event -- when brass exceeds the neck length of the chamber and "crimps" itself onto a bullet. THAT is a recipe for very dangerous pressures. Over trimming the brass cheats you out of neck on your cartridge, reducing the case capacity in some instances, since you have to seat the bullet deeper, But with even 140gr bullets in a 280 AI, you will not have trouble getting enough bullet in the neck for adequate neck stability (old rule is seat same distance as the diameter of bullet, so .284, NOT counting the boat tail). So your neck lengths are NOT the issue, IMO. I WOULD sort by manufacturer, then trim them all to the same length. If some are at 2.515, then cut them all that long. Or sort. But yes, using cases of varying length will affect neck tension and that affects accuracy, though not usually pressure.</p><p></p><p>** You have the Stoney River aka Hornady Case length comparator. It requires a modified case, which can be made yourself, as you are doing. I would NOT have FL resized. Instead, take a casse fired once or twice in YOUR gun (some cases don't reach full "fired" base to shoulder length till fired twice) case and just drill and tap the head. You should NOT have to be messing so much with sandpaper etc to get the neck to where it allows the bullet to move. That all being said, you probably have a decent test case now. I don't think its the case of your issues. See my top remarks first.</p><p></p><p>Finally, I too am new to the 280 AI, but not to reloading. I just posted up a thread here about best powders. I had tried RL-26 and was not overwhelmed, though that was in breaking it in. After reading a lot and based on some suggestions and two reloading manuals, I am going to try H4831sc next. Hornady and Nosler say max load of 60gr behind a 150grain bullet. Hodgdon's own site is more conservative at 57 grains. The usual caveats apply, start at least 10% below those numbers and work up. Caveat emptor. This powder choice does not give the most speed -- its reputed to give good accuracy which is my goal.</p></blockquote><p></p>
[QUOTE="cdherman, post: 1870773, member: 12282"] -- lots of questions to answer here. I'll try to give my thoughts.... ** You have once and twice fired brass, but you didn't make it too clear if that brass was fired in your cooper or not. If you have acquired brass fired in a different gun, you MUST full length resize and start over with your gun. Neck sizing or just touching the the shoulder back is not an option. If the brass was fired in your gun, then you can try and just back the shoulder down by .002". But here's another problem -- if you are using the expander ball with a FL die and the neck is work hardened and/or the ball/neck is not well lubed, you will "pull" the shoulder back out. This could be happening to you. I personally measure my brass thickness, use bushing dies, and then use a final Sinclair mandrel to make the inside diameters identical. Its all about neck tension. Or so I have read and believe. You are correct to measure the shoulder at .375, as that bushing is what Hornady says to use in the 280 AI. BUT, if the expander ball is pulling the shoulder "out" closer to the neck, you will NOT detect that with the case comparator. You are measuring at .375. Not right next to the neck. Hope this is all making sense. ** You have several lengths of brass. The max length listed in my Hornady manual (and they state they are using SAAMI) is 2.590". Trim to length is 2.530. Your measured length of 2.560" seems "short", but regardless, you are no where close to the real dangerous event -- when brass exceeds the neck length of the chamber and "crimps" itself onto a bullet. THAT is a recipe for very dangerous pressures. Over trimming the brass cheats you out of neck on your cartridge, reducing the case capacity in some instances, since you have to seat the bullet deeper, But with even 140gr bullets in a 280 AI, you will not have trouble getting enough bullet in the neck for adequate neck stability (old rule is seat same distance as the diameter of bullet, so .284, NOT counting the boat tail). So your neck lengths are NOT the issue, IMO. I WOULD sort by manufacturer, then trim them all to the same length. If some are at 2.515, then cut them all that long. Or sort. But yes, using cases of varying length will affect neck tension and that affects accuracy, though not usually pressure. ** You have the Stoney River aka Hornady Case length comparator. It requires a modified case, which can be made yourself, as you are doing. I would NOT have FL resized. Instead, take a casse fired once or twice in YOUR gun (some cases don't reach full "fired" base to shoulder length till fired twice) case and just drill and tap the head. You should NOT have to be messing so much with sandpaper etc to get the neck to where it allows the bullet to move. That all being said, you probably have a decent test case now. I don't think its the case of your issues. See my top remarks first. Finally, I too am new to the 280 AI, but not to reloading. I just posted up a thread here about best powders. I had tried RL-26 and was not overwhelmed, though that was in breaking it in. After reading a lot and based on some suggestions and two reloading manuals, I am going to try H4831sc next. Hornady and Nosler say max load of 60gr behind a 150grain bullet. Hodgdon's own site is more conservative at 57 grains. The usual caveats apply, start at least 10% below those numbers and work up. Caveat emptor. This powder choice does not give the most speed -- its reputed to give good accuracy which is my goal. [/QUOTE]
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280 AI Reloading Input
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