I am friends with an older gentleman , that lived in prime elk habitat for 60 plus years. He has probably killed as many elk as any human ever. He killed most of them with a 243 and factory loaded 100 gr. bullets. Recently he moved up to a 6.5 Creedmore because of his diminished eye sight and figured he needed more power........ He also guided for 40 plus years and figured most carry more than needed. He lived in Grizzly country and respected the bears , but still did not power up to cover that situation either.