A little background... these started as once fired LC cases I bought online. While doing the initial sort I didn't find any with excessive shoulder growth indicating they were fired in a very loose chamber. I tossed out a few mangled and obviously bad cases, but other than that they looked very good.
After FL sizing only enough so that the bolt had a decent amount of drag on it when closing, I ran them through my 223AI for fireforming. While fireforming 600 cases I lost 25-30 cases to lengthwise body splits that look almost the same as these, and another 15-20 cases to small neck tears.
The fireformed brass is now on its 3rd firing as a 223AI, and I'll lose about 5-10 of the fireformed cases every 600 rounds to the same kind of lengthwise case split/fissure, and another 5-10 or so to very small partial neck tears. I sectioned 4 cases that failed in the last batch to look at the wall thickness and I don't see any thinning at the web that may have initiated the failure or indicate possible case head separations in the next firing.
My current thought is the brass in the body of the cases is a little hard / brittle, and when fireforming and the case stretched instead of stretching evenly radially to form to the larger AI chamber most of the brass growth was taken from one area which lead to a vertical thinning in one area of the case. Questionable brass quality would also explain the occasional neck tear, although often times the small neck tears appear to be initiated by the small gouge in the neck that is left after extraction from an AR. I do anneal the necks every firing.
I'm planning on picking up 600 or so Lapua 223 cases soon and making those my dedicated 223AI brass and saving the once fired LC stuff for the AR's, but wanted to see what everyone though about these.
The loads are warm but not excessively hot, Quickload with the Ba tuned to my Labradar data shows the loads hovering around 51.5ksi... I've ran hotter in the past in my old 223 bolt gun and managed an additional 8 firings out of LC brass that started as Black Hills reloads (so 10 firings total) before the primer pockets were starting to get loose and never lost a single case to a split like this. Then again, that was 1999 headstamp LC brass and a regular 223 so no fireforming, and this new batch is all 2006 headstamp.
Appreciate any input...
Note on the pictures... I brushed the inside of the cases over the fissures with a stainless brush to remove some carbon, so those are the shiny vertical lines you're seeing. Also ignore the deformed necks, I squeezed a little too hard with the pliers while holding them on the belt sander.
After FL sizing only enough so that the bolt had a decent amount of drag on it when closing, I ran them through my 223AI for fireforming. While fireforming 600 cases I lost 25-30 cases to lengthwise body splits that look almost the same as these, and another 15-20 cases to small neck tears.
The fireformed brass is now on its 3rd firing as a 223AI, and I'll lose about 5-10 of the fireformed cases every 600 rounds to the same kind of lengthwise case split/fissure, and another 5-10 or so to very small partial neck tears. I sectioned 4 cases that failed in the last batch to look at the wall thickness and I don't see any thinning at the web that may have initiated the failure or indicate possible case head separations in the next firing.
My current thought is the brass in the body of the cases is a little hard / brittle, and when fireforming and the case stretched instead of stretching evenly radially to form to the larger AI chamber most of the brass growth was taken from one area which lead to a vertical thinning in one area of the case. Questionable brass quality would also explain the occasional neck tear, although often times the small neck tears appear to be initiated by the small gouge in the neck that is left after extraction from an AR. I do anneal the necks every firing.
I'm planning on picking up 600 or so Lapua 223 cases soon and making those my dedicated 223AI brass and saving the once fired LC stuff for the AR's, but wanted to see what everyone though about these.
The loads are warm but not excessively hot, Quickload with the Ba tuned to my Labradar data shows the loads hovering around 51.5ksi... I've ran hotter in the past in my old 223 bolt gun and managed an additional 8 firings out of LC brass that started as Black Hills reloads (so 10 firings total) before the primer pockets were starting to get loose and never lost a single case to a split like this. Then again, that was 1999 headstamp LC brass and a regular 223 so no fireforming, and this new batch is all 2006 headstamp.
Appreciate any input...
Note on the pictures... I brushed the inside of the cases over the fissures with a stainless brush to remove some carbon, so those are the shiny vertical lines you're seeing. Also ignore the deformed necks, I squeezed a little too hard with the pliers while holding them on the belt sander.
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