Weird wrinkle in brass

[Old Bob]

Like I said earlier, just turn them into functioning dummies. Brass cases I dare not shoot again are used to check both actions & magazines for functionality.

[Warlock]

I have had the same marks on starline brass re-sized in the same exact small base die as the one you are using.

What I did was to use a round diamond hone and wet/dry 1800 grit paper to ease the edge of the die (it was pretty darn sharp) that was causing the cutting/marking of the brass. Go easy with it and just ease the edge, it doesn't take too long and certainly doesn't take a lot of sanding/grinding to accomplish.

I then trashed all the brass that had those marks. I don't know if I got lucky or what but I haven't had any more cases marked like that.

[imaguy3]

I have had the same marks on starline brass re-sized in the same exact small base die as the one you are using.

What I did was to use a round diamond hone and wet/dry 1800 grit paper to ease the edge of the die (it was pretty darn sharp) that was causing the cutting/marking of the brass. Go easy with it and just ease the edge, it doesn't take too long and certainly doesn't take a lot of sanding/grinding to accomplish.

I then trashed all the brass that had those marks. I don't know if I got lucky or what but I haven't had any more cases marked like that.

Why did you go to the work to clean them up just to trash them?

[Warlock]

I didn't word that very well.

I was in the process of re-sizing a few dozen pieces of starline brass and happened to notice the same marks as seen above.

To me, it looked like the dies were shaving brass off the same area as pictured above. At that point I stopped re-sizing the empties and started looking at my set of dies.

While I was messing with removing the expander from the die, I felt the die scrape my finger nail and pretty much figured the RCBS die escaped the factory and the QC process so I used the round diamond hone to break the sharp edge and then did a wet sand to blend everything together. The process worked out pretty well for me and at that point I decided to not send the die back to RCBS to have it finished and polished.

At that point I felt the brass that I did run through the die before the edge was broken and polished wasn't safe to reload and threw the three pieces of brass in the garbage.

Sorry about that.

[James3]

I find this very interesting as I am having the same issue with starline brass. I took 2 once fired starline cases and loaded them to a mid level with a 123 grain bullet, fired them and then resized. You can see the belt just starting to form. I thought I had a die issue but I have not seen this in my hornady brass. I do realize that these could be the high power cases from load development but I am having a 50%+ rate of this happening. This is in 2 ar rifles so I think more investigation is in order. James3

[Klem]

This issue was posted on Snipershide last year.

https://www.snipershide.com/shooting/threads/new-6mm-advanced-rifle-cartridge.6992101/page-9

A discussion about Starline and how their cases are not as thick as they should be. Or maybe their brass flows too easily under pressure. Someone posted this picture of the belted magnum effect.

[lazyengineer]

While I don't think I have sufficient information to draw conclusions; I can't help but notice the few data-points we have, seem to be the premium brass (Lapua and Starline), and don't seem to include the common and more plentiful Hornady brass. There could be selection bias, so can't take it a lot farther then that, but so far, I find that interesting.

In a coincidental note, the one out-of-nowhere Kaboom reporting I've seen, is here with a thread going on right now; with a Grendel casing. That one was using Lapua brass as well. Again, so few data points one can't conclude much, but I will say, of all the Kabooms I've read (many), this is probably the only one that doesn't involve a degree of suspect of the typical error's such as barrel obstruction or error in powder charging. But just a straight up pressure release through the case wall due to a minor item (embedding in the lands), that basically would never Kaboom a .223 or many other casings. And hasn't kaboomed me with warm loads doing just that (before I learned the hard way that mag-length doesn't automatically equal off the lands still). And I did that running Hornady brass. Again, that one reported Kaboom was with a premium Lapua casing. The failure was out that bottom area, right about where that ring is showing up.

Maybe none of this means or indicates anything and there is no relation. But it caught my eye. You'd think surely Hornady brass makes up the majority of brass being handled, yet none of these stories appear to be happening with Hornady. Heck, I run my stuff sometimes on the hot end, and am using Hornady brass that was black and full of dirt found-on-ground - that I had to wet-tumble with pins; and it's running fine. (well. so far!)

I'd be curious to see a cross-sectional comparison (or a case-capacity comparison), of Hornady vs Lapua vs Starline. A manufacture is motivated to maximize case volume, nowhere moreso than little Grendel. Make the web at the head just a little bit thinner, and the walls flare into meeting that head just a little bit thinner, in a barrel with a chamber support just a little bit rounded more....

[VASCAR2]

[bsteiner27]

About a month ago I had the same problem resizing some Starline brass. It was shot out of my AR with a 18" Faxon barrel suppressed. These were twice fired and the load was either 120gr eld-m with 27.3gr 8208 OR 123gr BTHP and 28.0gr 8208. I had a total of 11 like this out the the batch of about 60 or so I was resizing I was using homemade case lube (lanolin & isopropyl) and a Hornady resizing die set to bump back 0.003". At the time I was shooting these I was having problems with the gun locking back on the last round and was playing around with the adjustable gas block. Hoping this will help with getting to the bottom of this. My first thought was that I didn't lube them enough and was working the ram to fast and "pushing" the brass down to the base, but if that was the case I would assume I should of been having some stuck cases.

20211129_134117 (Copy).jpg

[imaguy3]

About a month ago I had the same problem resizing some Starline brass. It was shot out of my AR with a 18" Faxon barrel suppressed. These were twice fired and the load was either 120gr eld-m with 27.3gr 8208 OR 123gr BTHP and 28.0gr 8208. I had a total of 11 like this out the the batch of about 60 or so I was resizing I was using homemade case lube (lanolin & isopropyl) and a Hornady resizing die set to bump back 0.003". At the time I was shooting these I was having problems with the gun locking back on the last round and was playing around with the adjustable gas block. Hoping this will help with getting to the bottom of this. My first thought was that I didn't lube them enough and was working the ram to fast and "pushing" the brass down to the base, but if that was the case I would assume I should of been having some stuck cases.

[ATTACH=CONFIG]18424[/ATTACH]

See yours look much more uniform and regular than mine. Mine don't actually go all the way around the piece of brass like yours appear to. Mine are just sort of on one side. Weird.

I use the Hornady one shot spray... these pieces of starline brass were on their 3rd firing/resizing. They have seen various loads/charges over the couple years, ranging from 26.5 -28 gr of 8208xbr, always with a 123gr SST and always in the same gun. Interesting.

[CoyoteConquest]

I know this a couple of weeks old but that isn't from sizing. It's from shooting. The Grendel bolt face is .136 most bolt faces are .125. That's why you have the type one and type 2. Type 1 or 7.62x39 bolt face is .125 vs the type 2 Grendels .136. The grendel has a little bit of case that isn't supported so the unsupported part can do that every once in a while. Those were probably loaded a little hot.

[LRRPF52]

I know this a couple of weeks old but that isn't from sizing. It's from shooting. The Grendel bolt face is .136 most bolt faces are .125. That's why you have the type one and type 2. Type 1 or 7.62x39 bolt face is .125 vs the type 2 Grendels .136. The grendel has a little bit of case that isn't supported so the unsupported part can do that every once in a while. Those were probably loaded a little hot.

[CoyoteConquest]

You may be right but I've never seen it happen to an LBC variant of the cartridge

[imaguy3]

Just an update. I had contacted Ballistic Advantage about this barrel when I encountered this issue, b/c of accuracy issues too, they have informed me they are replacing it under warranty. I asked what they found wrong with it but haven't heard back yet.

I also contacted hornady (since it was their die) and sent them these photos of one piece I cross sectioned. Hornady believes it is a chamber issue with the barrel, possibly excessive headspace.

[lazyengineer]

Just an update. I had contacted Ballistic Advantage about this barrel when I encountered this issue, b/c of accuracy issues too, they have informed me they are replacing it under warranty. I asked what they found wrong with it but haven't heard back yet.

I also contacted hornady (since it was their die) and sent them these photos of one piece I cross sectioned. Hornady believes it is a chamber issue with the barrel, possibly excessive headspace.

thanks for this. One technique that can help with the cross sectional analysis, is to try and polish that a bit, so that the metal galling(?) that naturally occurs and can obscure some of the features, is taken care of. It will make it more obvious to see things. Obviously you don't have to - I'm Not Your Supervisor! But if you do have access to some medium and fine sand paper, a little time rubbing on the area around the case-head, may reveal more features of the brass flow and countour changes there.

Regards, thanks again for the photos!