who makes the barrels??
Alexandar Arms is the original manufacturer of both Grendel & Beowulf rifles, you can buy a barrel directly from them.
Alexander Arms: Welcome to the Revolution
Double Star also makes barrels for the Grendel rifles, I think my brother mentioned that Double Star was a sort of sister company for Alexander, but I can't remember exactly, so don't take that as fact.
DoubleStar AR-15 M-16 Rifles and Carbines for Sale Service M-60 Parts
Another up side of this is that the .243 Winchester is .308 necked down to 6 mm. That means that the bolt, magazines and receiver for the .243 can be used to convert the rifle to .308 by simply changing the barrel. Anyone else out there shooting the Panther series rifles by DPMS?