6mm ARC

[BluntForceTrauma]

Could be but, I wonder if it wasn’t simply just a “legal/safety” issue to keep the “Grendel” from being able to also fit in the chamber?

I agree that this is the reason.

A 6mm Grendel case should actually be longer, about 1.590 — if I recall — whereas the 6.5 Grendel is 1.520, to get more powder in for the lighter and shorter weights of 6mm bullets.

But, if this is geared to longer 6mm bullets, then it looks like a Hornady design where they are planning on the boattail ending and the bearing surface starting at the neck/shoulder junction.

This has been begging to be a factory round for a LONG time. it was inevitable and congrats to whoever did this (be surprised if it's not Hornady).