I got to test the N550 today and loaded 55, 55.3, 55.6, 55.9 grains in groups of 4. 55.3 took home the prize and awarded me a .497" 4 shot group at 100 yds. the average speed for those was 3015 fps. My ballistic calculator says I need 6.25" inches for a 400 yd zero, my Zeiss 3-9 is 4 minutes from the intersecting crosshair to the point of the lower post, so I adjusted my poi to 2.25" above center. I can now hold the point of the lower post on a critter at 400 and hold dead on. I didn`t shoot the 55.6 or 55.9 as the chrono at 3015 was good as I needed it to be.