Re: Need your opinion
I'll cast a dissenting vote. I stopped using the .300's and went back to the 7 rem mag shooting 180 gr Berger VLD's. Less recoil. I can't see an appreciable difference in killing ability, but I am certainly not the most experienced long range guy here.
As for factory ammo, I would also suggest for serious long range shooting, reload. You really need to be able to tailor your handloads for best accuracy. That said, I know there are some custom manufacturers that guarantee half-moa, or less, with match grade .308 loads. Maybe they would similarly expect the same level of accuracy with similar .300 WM loads. There are outfits like Best of the West and Gunwerks that load matchgrade ammo, and I think will also work up a load in your rifle, then load for you. Just depends on how much $ you want to put into it. For the right price you can have your cake and eat it to.