47 gr's is THE book load with a 150 (you're shooting a 155). Can't see any reason to go over, especially given that group. You can certainly play with seating depth, though I'm not sure why at this point.

I'd go shoot three more groups @ 47gr's and see if the original group result holds up. If not, then play with seating depth.

“Perfection is Achieved Not When There Is Nothing More to Add, But When There Is Nothing Left to Take Away” Antoine de Saint-Exupery