I've never owned one or shot one, but IMHO there are no flies on the .358 Norma Magnum!
(I do own rifles in .338 Win Mag, .35 Whelen, 9.3x62, and .375 H&H. Of these, I have hunted and taken plains game in South Africa with the 9.3x62 and the .375 H&H. I have not hunted with or taken any game yet with my .338 Win Mag and .35 Whelen.)
My two cents.... Cheers!
-Bob F.