wigwam, 2000MR makes perfect sense in the 358 as it is my go to powder for the 338 Federal with 200 gr bullets. I tend to think of the 338 Federal as the cartridge the 358 was meant to be, or the modern day 358, in that it shoots 200 gr. bullets faster. Since those bullets are more streamlined with better BC's, they shoot flatter with more energy downrange. Same goes for the 338 RCM, I think of it as the modern day 350 Rem Mag for the same reasons. Of course, with you 315 gr. bullets, that a whole other story. And then we must remember that when W-W came out with the 358, there were no factory 338's. Bob!!! 8)