If we restrict our field of concern to OPEN SIGHTED big bores used on Dangerous Game at "close" range 45+ cal and up--458WM, 450/470 Doubles, 500 NE,505 Gibbs/500Jeffery/500 AHR, 577NE, etc---

How much accuracy do we need at 50 yds, 100yds,?150 yds??

Do we file sights and zero them at 50 yds? And also see where they group at 100yds?

What are the upper limits tolerated? Is an upper limit of 2" accuracy at 50(4" at 100) adequate for large DG?
What size kill zone is adequate?

Forum members, what do you think?