6.5 Grendel brass to 6ARC to 22 ARC?? 12.5" AR Plans

[Feral Jared]

I'm getting out of the 6arc bolt gun to shift my attention to other SA rounds like 22CM, 243, and 7-08). When I first loaded into the 6arc, I bought a couple hundred pieces of 1x Lapua grendel brass to convert. No issues there that I could tell, and accuracy was acceptable. Since I still have the components, I'm thinking I'll do a 12.5" AR upper, and was initially thinking I'd do it in 6arc- but now I'm thinking a little more about building it in 22arc, so I'm wondering about the viability of the cases I have on hand.

Has anyone had any neck thickness or other issues with forming 6.5 grendel brass to 22arc (by way of 6arc for my case)

I'm also interested in hearing thoughts on the two rounds in a 12.5" gas gun. No real purpose for this one other than having a short. handy AR that can reach out a bit for pests, and possibly the occasional deer.