Which chamber for a custom bolt gun?

[Hooz]

Bolt gun choice would have to be .260 or 6.5 Creedmoor. Still short action and readily available components.

It still cracks me up. Every time I see someone ask something about a bolt-gun project, there are multiple people who say this sort of thing. It happens on all gun forums.

If I wanted a short-action, or if I wanted a .260/6.5x47/6.5 Creedmoor, that is what I would build. But, I don't. I want a smaller-than-short-action ("micro action") that shoots 6.5 Grendel ammunition.