Split 9mm case

[diopter]

Saw this a few days ago at local club. Someone was shooting an AR style 9mm carbine and had his second split case with this gun using X-metal loads.
Poor guy could not get the front of the case out of the chamber on the range. Said he did have a shell extractor at home.
Has no upper, does not hinge open. Barrel has to come out like a 22 semi-auto

Second picture is next to 45ACP for size comparison.

 

[colinjw]

That primer looks like it has a large crater on it.
Is that a sign of a very high pressure load ? Possibly way too high ??

 

[bigedp51]

Google "stepped 9mm case" and see all the images of split cases.
https://www.google.com/search?q=stepped+9mm+case&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiAn_vSv7jdAhUyxVkKHdi4B_cQ_AUICygC&biw=1366&bih=613#imgrc=_

Bottom line in many reloading forums you are warned to not buy or reload these type stepped cases. When they are fired the brass is weakened above the step. If you use range pickup brass and find cases like this just put them in the scrap brass bucket or in the trash. Even if these type cases look OK resizing them will weaken the cases further and they will split and fail.

Below is a very good video with illustrations on why these type cases split.

"Stop using this garbage brass in your PCC already."
https://waynematteson.com/2017/04/07/stop-using-this-garbage-brass-in-your-pcc-already/

 

[diopter]

Interesting how the head stamp font is identical on all the stepped brass. Must all be made by one factory for different buyers.
the "9mm LUGER" is Identical on all the cases.

 

[OkayShooter]

With xmetal reloads, Its unknown how many times the brass been reloaded. Ive had a few split cases, never any separations.

 

[bigedp51]

The video explains it is the case design with its step and thinner upper case walls that is the problem. And if you or someone else reloads the case you will have problems.

As I stated in my first posting you can read about this in any pistol forum and it is a case design problem.

Brian Enos's Forums

Case head separation- who has experienced this?

https://forums.brianenos.com/topic/256820-case-head-separation-who-has-experienced-this/

MaxxTech- Stepped to a whole new level
https://forums.brianenos.com/topic/237712-maxxtech-stepped-to-a-whole-new-level/

If these cases are reloaded it will cause a pressure increase because these cases have less case capacity. And this is on top of the case being weakened and stretched just above the step.

 

[Icefire]

Yep stepped case from the picture!