300BLK case failure

[The_Eric]

I was out shooting my AR chambered in 300BLK the other day and while picking up my brass, I found one with a split case. This was the only one that I found that day and the only one that I've ever noticed. The gun cycled perfectly every shot and I didn't notice any variability from round to round. Is this simply an anomaly, a quirk of this particular brass or perhaps an indicator that something more serious is going on?

FWIW I was shooting Magtech 123grn ammo

 

[JohnnyJohnson]

Do you reload? looks like that case was reloaded to hot.

 

[The_Eric]

Do you reload? looks like that case was reloaded to hot.

No, that was a factory load.

 

[burbguy82]

That looks pretty jacked up for new brass.

Could be high pressure load, incorrect chamber ream, just a bad case.......I would look at other brass and see if others look similar. Use the extractor or ejector markings on the case as reference.

If other look nice, I would say bad case=proceed with shooting

 

[JohnnyG]

That round was overloaded for sure. All of the imprints of the boltface, including the cutout are visible on the case head. Also evidence of primer pocket expansion and leakage.
Every Garand comes with a broken cartridge removal tool in the buttplate. So even way back, this sort of thing was known to happen.

Not sure where CBC is made, but I'd try to let them know.
Now, all of this assumes that nothing was restricting the bore or action at the time of firing.

 

[The_Eric]

That round was overloaded for sure. All of the imprints of the boltface, including the cutout are visible on the case head. Also evidence of primer pocket expansion and leakage.
Every Garand comes with a broken cartridge removal tool in the buttplate. So even way back, this sort of thing was known to happen.

Not sure where CBC is made, but I'd try to let them know.
Now, all of this assumes that nothing was restricting the bore or action at the time of firing.

The box state "Made in Brazil" - I'm guessing most of Magtech ammo is made there?

 

[The_Eric]

Here's a couple of shots of other brass from the same box and same outing

 

[JohnnyG]

That stuff is loaded to the max, lots of pressure signs. I think your chamber could use a good cleaning too, btw.

Was it exceptionally hot that day? Some powder can react to excess heat in that way. Some will actually go the other way with heat, like the old 452AA.

 

[wwillson]

imprints of the boltface, including the cutout are visible on the case head.

Agree and the cracked case, firing pin strike looks like a crater instead of a dimple, and the partial case head separation is a sure sign of high pressure. I have experience all of these on over charged rounds. Maybe someday I will tell the story (admit) how I over charged the .223 reloads by accident.

 

[Ursatdx]

Cases sure look abused for once fired brass.

Maybe someday I will tell the story (admit) how I over charged the .223 reloads by accident.

Do tell.

 

[wwillson]

Cases sure look abused for once fired brass.



Do tell.

I have told the story to a couple folks here. I'm sure they would agree that it's too embarrassing to tell.

 

[mrvmax]

Factory ammo is not perfect but no harm no foul -buy different ammo and move on.

 

[mrvmax]

Cases sure look abused for once fired brass.



Do tell.

You can probably still find online where a guy overloaded 45-70 and blew up his rifle and messed up his hand. I have pictures of that somewhere, I kept them to remind me to pay attention when I load. I have made one mistake in the last 20 years, I did not charge power to 300 blackout and luckily I was not rapid firing. I noticed a different sound and stopped shooting. The bullet was lodged in the barrel from the primer. I pulled all that ammo and it was the only one without powder and I have never done that again, I changed the way i verify powder charge.

 

[wwillson]

Cases sure look abused for once fired brass.



Do tell.

https://bobistheoilguy.com/forums/threads/how-complacency-lead-to-overcharged-223-cartridges.408006/

 

[Ursatdx]

https://bobistheoilguy.com/forums/threads/how-complacency-lead-to-overcharged-223-cartridges.408006/

THanks for that.

 

[JohnnyG]

Agree and the cracked case, firing pin strike looks like a crater instead of a dimple, and the partial case head separation is a sure sign of high pressure. I have experience all of these on over charged rounds. Maybe someday I will tell the story (admit) how I over charged the .223 reloads by accident.

Yep, I've done that too. Ruger #1 though, so just tough extraction.

 

[The_Eric]

Agree and the cracked case, firing pin strike looks like a crater instead of a dimple, and the partial case head separation is a sure sign of high pressure. I have experience all of these on over charged rounds. Maybe someday I will tell the story (admit) how I over charged the .223 reloads by accident.

Where do you see the partial case head separation? Spent brass analysis is something that I'd like to learn more about.

 

[The_Eric]

Factory ammo is not perfect but no harm no foul -buy different ammo and move on.

That can be done easily enough - I have 7 rounds left of that particular ammo, but I have a not insignificant amount of Magtech 115grn that I bought some time ago and I'd hate to get rid of it.

FWIW the ammo in question is 123grn but has no advertised velocity on the box. I could find a similar or perhaps the same in the a different box that is listed as 2230fps at the muzzle

The Magtech Tactical 115 that I bought is list as 2280fps at the muzzle