Is the Grendel a “PPU” case?

[Fess]

The 6.5 Grendel uses a variant of the 6mm PPC case. Arne Brennan sometimes called the non-SAAMI "match" variation of the Grendel the 6.5 PPCX. "X" stands for extended, since the shoulder of the Grendel is extended farther foreword than the PPC. The PPC has relatively longer neck. The 6mm PPCX, 6mmAR, and 6 Grendel are all similar cartridges developed from the extended-shoulder PPC/Grendel case. The 6mm ARC uses a shoulder length that is in between the PPC and the Grendel.

Here is a photo showing a 6mm PPC next to an extended-neck variant, the 6mmAR.
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