I would keep trying with the Barnes bullets, my model 70 is MOA with both 270gr, and 300gr. I could never get Nosler Partition to group well in my model 70, and have never tried A-Frames, but those Barnes bullets have great penetration, and weight retention.
I believe Barnes bullets have been pushed to the side a bit on DG, and I can attest thru my many one shot stops on non DG game, that the penetration is pass thru, and is frankly amazing for the penetration on quartering shots. I would load 300gr Barnes, or now they offer the 350gr TSX.
The only issue I have with Barnes is that they do not offer a solid in 375, but I have no issue with penetration thru hide, and bone with Barnes TSX. If I was concerned about penetration on "second shots" on DG, I may look to Woodleigh for a solid, although I have no experience with the Woodleigh in 375.