Seems pretty interesting from a company that makes very good rifles. https://www.primaryweapons.com/firearms/uxr/
The talk is mult-caliber, likely long stroke piston (that is PWS), and very modular. Video shows a decent amount and an internet search shows places that might be stocking it along with caliber conversions, including the 8.6 Blk, 7.62x39, 308, 223, 6.5 cm. I am looking to Friday. Just when I thought I was done buying guns!!!