SIG has been working on machineguns for military and the new gun uses 338 Norma Mag. Soldier Systems Daily did a good article on the gun. SIG also came out with a new optic that has various features integrated in to it.
http://soldiersystems.net/2019/01/23/shot-show-19-more-details-on-sigs-new-338-norma-mag-machine-gun/
From: Soldier Systems Daily