Odd case fissures on 223AI brass

[Kiba]

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.

 

[Milo 2.5]

Have you looked at your chamber with a borescope?

 

[Campguy308]

Wtf is the deal with the first 2?

 

[Kiba]

Have you looked at your chamber with a borescope?

Yep, I have checked it in the borescope. These have actually been through 2 rifles. I fireformed and did the first 2 firings as 223AI in my Tikka T3 that Tooley chambered,and lost some cases during fireforming and also on the next firing. Chamber on the Tikka looks great, no excessive diameter growth in the body between FL sizing and firing, etc. The last firing has been through my new 223AI Nucleus that PVA chambered. Again, the PVA chamber looks great and no huge body diameter difference between FL sized and fired, but I lost those 4 cases due to body splits and another 4 or 5 due to small neck splits. No excessive neck clearance in either rifle and I use a bushing die and anneal every firing, so the neck splits are not due to overworking the necks. The chamber on the PVA barrel is a little tighter than the Tooley barrel, I had to drop the FL die 0.002"; not a huge difference.

I forgot to mention I've also had a couple of pieces of this same batch of brass have neck splits and 1 or 2 vertical body splits just like the above pictures in my AR which is a regular 223 chamber-- that's why I'm leaning towards bad brass... just wanted to see if anyone else has ran into this.

Even though the cases come out of the chamber looking like hell you cannot tell on the target or chronograph that a case has just experienced a vertical split. There's no big puff of gas that I notice as the split is nearly fully contained in the chamber. I had 2 split on my last range trip and the bullets hit the same spot on the target and the chronograph showed the velocity of the split case round was within 10fps of the previous and next shot fired. Only reason I noticed is I was single loading for a ladder test at the time and you can't miss that split when putting the fired case back in the ammo box.

Wtf is the deal with the first 2?

What do you mean? If you mean the crunched necks, that's because I squeezed them too hard with the pliers while I was belt sanding them down to section them, LOL. Ignore the deformed neck and body, that's just an artifact of holding and sectioning them. I just wanted a better view inside to look at the splits and also look at the thickness of the web area and just above the web. They don't come out of the gun that way... LOL!

 

[Campguy308]

I have experienced the same thing with pre-processed LC brass in my AI. It was from a lot that I bought years ago from an online supplier. I have not had that problem with any other brass. I have some new processed LC brass from a different supplier that I'm going to try soon.

 

[Milo 2.5]

As thick as the brass is in that same area I'm thinking it was fired in a bad chamber, maybe before you bought it.
You can do what you like, but I'd quit firing it. I think it will etch your chamber at some point like bolt face pitting, barrel steel is not really hardened like a bolt is.

 

[Tx_Aggie]

I've come across a couple of batches of once fired lake city where nearly every piece had excessively short headspace (.010 -.015 or even as much as .020 short of 1.438"). One lot was brass that was labeled as only having been de-primed and swaged, while a second had also been re-sized and wet tumbled by the re-seller.

I was splitting the second lot with a friend who also shoots a 223 AI. Before I got around to using any of my half by buddy tried fire forming some of the brass without realizing there was an issue, assuming it would be fine because it had already been sized by the seller. He ended up with lots of issues, including FTFs because of brass being too short, case head separations, and I think some split cases similar to yours. Bad times for sure.

 

[Kiba]

As thick as the brass is in that same area I'm thinking it was fired in a bad chamber, maybe before you bought it.
You can do what you like, but I'd quit firing it. I think it will etch your chamber at some point like bolt face pitting, barrel steel is not really hardened like a bolt is.

I agree. As much as I hate to have to go through fireforming again I think I'm going to junk this entire batch of brass. I just borescoped the chamber after Friday's range trip and there are a couple of smudged blackened areas with embedded brass in the chamber from these splits. 1 of the soot tracks extended all the way out of the chamber; I believe this was from the second case from the left in the pictures as that crack extended back the furthest and you can see some of the soot impinged on the rim of the case. I used a .45 caliber bronze brush to clean the chamber real well, and while all the brass and soot cleaned up it looks like there are a couple of tiny pits where the gas "torched" into the chamber wall of this brand new barrel. The pits are tiny and don't show up on fired brass, but I figure I better stop now as this barrel is brand new and has a lot of life left.

I've come across a couple of batches of once fired lake city where nearly every piece had excessively short headspace (.010 -.015 or even as much as .020 short of 1.438"). One lot was brass that was labeled as only having been de-primed and swaged, while a second had also been re-sized and wet tumbled by the re-seller.

I was splitting the second lot with a friend who also shoots a 223 AI. Before I got around to using any of my half by buddy tried fire forming some of the brass without realizing there was an issue, assuming it would be fine because it had already been sized by the seller. He ended up with lots of issues, including FTFs because of brass being too short, case head separations, and I think some split cases similar to yours. Bad times for sure.

The brass I bought was tumbled/deprimed/deswaged but not sized, I checked every one with a Wilson case gage and also a bump gauge comparator before sizing them. Most of the brass would have needed a .003" shoulder bump to get the shoulder length to match the length of cases that come out of my AR after firing, so it's not like the brass was excessively stretched from a loose machine gun chamber nor did the seller oversize the crap out of them before selling them. I ran them through the 223AI FL die backed off a couple thou mostly to clean up the necks before loading, and the bolt was a pretty firm close on the cases on the initial firing.

Just wondering if this is bad brass from Lake City, or if something was done to them while sitting in storage or during cleaning/deswaging that embrittled them. A couple years back I had some horrible Winchester 223 brass; a friend bought it as new loaded ammo and shot it once then gave it to me. About 10% of the necks were split on the once fired cases he gave to me, and I lost over 75% of those cases to neck splits in only 2 reloads-- and that's annealing every time and using a bushing die and not overworking the necks.

Anyways, going to toss this batch of brass and start over. Just ordered 700 Lapua 223 cases from Brownells, with the current 10% off coupon plus my 03 FFL pricing and free 2 day shipping I couldn't pass it up. That should last a couple of barrels easily provided I don't get stupid with the loads and trash the cases.

 

[918v]

Maybe this brass came in contact with ammonia which made it brittle?

 

[Kiba]

Maybe this brass came in contact with ammonia which made it brittle?

Exposure to ammonia or an ammonia containing compound is a possibility I considered... It's once fired brass of unknown origins and treatment before it got to me.

I forgot I loaded 600 rounds of this same brass for a friend's 223 bolt rifle... Not a single body spilt in his batch after the first firing in his rifle.