Marrakai
Don't feel like the lone ranger, about 1/3 of my rifles do the same, 4 - 10 inches high with good loads shooting the right weight bullets at the correct speeds. Tried holding low but never seeemed to remember when there was fur in the sights, had a couple of lung/shoulder shots turn into spine jobs. Now I just make a new, higher, front sight, one less thing for me to think about when hunting. Just finished one this last weekend for a 375/2.5 that was shooting 9" high. The old sight gets a labled plastic bag with several of it's mates in the parts box.
Enjoyed reading of your success with the 577/500 on buff, none of those around here, so I'll have to see if I can find a good hog this fall for mine to work on.
Best.