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Posted: 9/18/2016 8:21:37 AM EDT
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Hi Guys...
I'm loading for a new 280 Ackley Improved. I've bought new virgin Norma 280Rem brass, which likely isn't Lapua quality but I thought should be fairly decent. I tried a regular starting load for 280 Remington as a fire forming load. I get really rounded, not-nearly-filled-out shoulders. So I've bumped it just a little bit, load so the bullet fully engages rifling, and fire form, getting nice clean, relatively full shoulders on the fire formed case. It's barely just enough to fill out the Ackley Improved shoulder and give me proper headspace on subsequent firings. Accuracy with this fire form load is VERY good. I need to chrono them, but if speeds are reasonable, this fire form load may be a hunting load. I'm getting one raggedy cloverleaf at 100 yards. Here's the deal: I've getting some very small cracks in some of the necks after as little as two or three firings. Brass isn't growing much (thank you Ackley Improved). But on 5 of 100 cases, Ive gotten small, perhaps 1-2mm hairline cracks, about middle of the neck, running parallel to the bore. In a few of these, I've gotten two or three of these very small cracks... These aren't the typical "old brittle hardened overworked brass" big assed neck failures. Just little, hard to see but still there neck cracks.... They don't even seem to be 'venting' gases on firing. For what its worth, I'm NOT working these cases hard after that initial firing. I'm neck sizing only, using a Redding neck size die. The shoulder and body aren't being worked at all after that initial fire form with virgin brass. I've gotta say I'm a bit disappointed.... Anybody else find similar issues? Fro |
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What type of dies are you using? There are two variations of the .280 AI. An older version and newer version most gunsmiths are currently using. If the die does not match the chamber its very frustrating.
Lots of people thought they could buy buy virgin Nosler .280 AI brass and run. It's not that easy I learned this the hard way when my son had a very well known smith make a .280 AI. While this sounds extreme, I would try to have dies made with the same reamer the chamber was cut with. Or send several pieces of once fired brass to Redding and have a custom die made for your rifle. |
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I'm sure your know this...but, Time to anneal those necks and shoulders.
You may have gotten a brittle batch of Norma ( or any manufacturer, for that matter ) brass. Remember , not all brass is made of the same "brass" and manufacturing process. http://www.accurateshooter.com/technical-articles/x-ray-spectrometry-of-cartridge-brass/ |
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Thanks Nigla.... Yah, the 'to different 280 AI" thing is a pain in the ass. I've using a Cooper, and according to Cooper its the original, non-Nosler chambering. And I'm using appropriate dies as well.
It's kind of a stumper. So, failing all else, I'll try annealing. Seems extreme after TWO firings. Figure $1 each for the cases, plus the cost of powder, primer, bullet and barrel life to fire form to AI. Those are expensive cases if they last but two or three firings... I'll try annealing with hornadys kit and see what happens. Fro |
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Quoted:
Hi Guys... I'm loading for a new 280 Ackley Improved. I've bought new virgin Norma 280Rem brass, which likely isn't Lapua quality but I thought should be fairly decent. I tried a regular starting load for 280 Remington as a fire forming load. I get really rounded, not-nearly-filled-out shoulders. So I've bumped it just a little bit, load so the bullet fully engages rifling, and fire form, getting nice clean, relatively full shoulders on the fire formed case. It's barely just enough to fill out the Ackley Improved shoulder and give me proper headspace on subsequent firings. Accuracy with this fire form load is VERY good. I need to chrono them, but if speeds are reasonable, this fire form load may be a hunting load. I'm getting one raggedy cloverleaf at 100 yards. Here's the deal: I've getting some very small cracks in some of the necks after as little as two or three firings. Brass isn't growing much (thank you Ackley Improved). But on 5 of 100 cases, Ive gotten small, perhaps 1-2mm hairline cracks, about middle of the neck, running parallel to the bore. In a few of these, I've gotten two or three of these very small cracks... These aren't the typical "old brittle hardened overworked brass" big assed neck failures. Just little, hard to see but still there neck cracks.... They don't even seem to be 'venting' gases on firing. For what its worth, I'm NOT working these cases hard after that initial firing. I'm neck sizing only, using a Redding neck size die. The shoulder and body aren't being worked at all after that initial fire form with virgin brass. I've gotta say I'm a bit disappointed.... Anybody else find similar issues? Fro Question-are the 5 cases the same ones you used for the initial fireform loads? When you move the brass as much as you do when fireforming to the A.I. shape, it work-hardens very quickly. Those rounded-shoulder cases should have been annealed after the failed fireform attempt, if not then I'm guessing that's what the problem is. The rest of the cases should be fine, but probably should be annealed before long. |
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