I have a 455 American that was shooting quarter size groups at 50 yards from a bench resting on my shooting bag, using cheap Federal ammo. I put a bipod on it and started shooting CCI Mini Mags, but now I can't hold any kind of a group. Even after going back to the cheep ammo that was grouping OK, I still can't seem to get decent groups. That leads me to believe the issue is somehow related to the bipod (it's the type that attaches to the sling stud). Has anyone had a similar experience or have any suggestions?