Yes, I would definitely try different ammo then. As I said, buy 2 different brands of ammo and fire an initial 5 shot group at separate targets.
In general, I would expect most modern rifles to do far better than the groups you're shooting now. If you were shooting handloads, I'd have all kinds of ideas as to what is causing this scattering, but with factory ammo your best bet is to change brands.
Grouse