American Rifleman tested the Storm rifle, and the best group they could get at 25 yards was 2 inches. that is more than 8 MOA.
That's strange. I have gotten better groups with a rental Storm with UMC 9mm ammo. My groups (leaning over with my elbow supported) were about silver dollar size at 30 yards.
I would leave it stock but if you feel the need, I would put a red dot on it of your choice, not a scope.