I once bought a case of .223 Rem UMC FMJ and it didn't shoot great in my bolt-action. One day, I wanted some varmint ammo, so pulled the bullets on some UMC and replaced them with Sierra 55 grain spritzers and shot them for groups. They shot about 3/4" at 100 yards, while the UMC bullets in the same cases and powder charge shot only 1 1/2".
If I can't be with the rifle I love, I love the rifle I'm with!!