I will, as a general rule, set BUS to zero at 50 yds with a 55 gr. bullet.
Same here. A 50 meter zero puts me about 1" high at 100 meters and back zeroed at 200. Using a no-magnification red dot I can put rounds on paper plates all the way out to 300 meters with this zero, and can still keep them in a torso sized silhouette at to almost 400. So 50 is definitely my preferred zero, though I'd recommend you also verify your zero at 200 as well.