Chris
I would think Barret Rifles would be the best place to ask.
Of course, any reputable barrel manufacturer can furnish a barrel blank with a profile that offers sufficient material around the chamber end. For some reason,I suspect the usual 1.250 would be a tad small.
I looked at the ballistics of this beast. A 400 grn bullet at 3250 fps. That will get your attention on both ends of the Rifle........jackie