I finally shot my new Winchester Model 70 Super Shadow 300 WSM. I was getting some pretty eratic shot groups with the Winchester 150 Gr XP3 ammo. I was kind of disappointed because the ammo is so expensive, and I used an entire box of 20 rounds but still finished without a zero! (at 100 yards)

I was told that the 150 Gr might be too light for the 300 WSM and unpredicatable, but Winchester says otherwise. I'm almost positive it's not from the flinch, the recoil isn't bad at all. I was thinking about switching to the 180 Gr XP3 instead. Some people say rifles are picky about ammo? I know it's not the scope, I have a Leupold VX-II mounted on it.

Any help or ideas here would be appreciated!!