Numrich has factory barrels for a price I can be happy with, but they have the threads for the factory muzzlebrake. It is stated that a thread protector is included but I searched their sight and can not find a factory muzzlebrake (I have bad success navigating their database). Some options I have are as follows

buy and shoot with thread protector as is.

I have a factory muzzlebrake on a 300rum, I guess I could swap this when I change barrels.
is the thread for a factory brake 9/16x28 something that would work with other aftermarket muzzlebrakes?

or, I could leave well enough alone and not buy another barrel that I dont have time to shoot. But the 375 is a granddaddy and I am a sucker for chamberings with history.