[Yo-Yo]

I missed where it said 80k psi.

The SAAMI-recognized civilian version of the 6.8x51 is the 277 Sig Fury.

It sports a three-piece case consisting of a brass body, a steel case head, and a locking ring to attach the two together.

With a steel case head, you'll reduce case head failure from such a high pressure round, and minimize extractors ripping rims off of the cases.

[Magnum44]

Holy crap. Who can afford ammo like that? sigh...I know...the tax payer. :(

[Big Red Badger]

5.56/223
Is Obsolete now.

[T.B. Yoits]

The steel part of the case may solve a problem with head failure from high pressure rounds and minimize the extractor breaking the cartridge rim but mixing steel and brass will lead to corrosion.

..and such corrosion will lead to head failure from high pressure rounds and the extractor breaking the cartridge rim.