Put a Holland MB on my 300 WM. I have a #3 BRUX on mine and it is "thin". Can't remember off hand what it measures at the muzzle; but you should be ok. It is not a match in contour however. There is a bulge with the brake. Doesn't bother me and it sure tames the recoil.
+1 on Holland's QD MB, I have one on my Savage 111F .300 Win Mag with sporter contour (.590" at the muzzle IIRC) that works extremely well.