the .375 Ultra is about the same step up from the .375 AI/.375 WBY as going from .375 H&H to H&H AI/WBY

capacities in H20 from QL

.375 H&H---95 gr.
.375 AI----105 gr.
.375 WBY---105 gr.
.375 RUM---117 gr.

.378 WBY---137 gr.

i'm shooting 235 gr Barnes TSX bullets @ 3100 fps from the SPS and 260 Nosler Accubonds @ 3000 fps from the XCR II.

Guns don't kill people, drivers with cell phones kill people.