Specifically the .338 bullets.
Actually two tests: Browning is making ammo, including .308 with a nice nickel-plated case. Found some long enough to form to .338 Federal, and you've got to try them out.
Two test loads here. The one I'd settled on was either Lake City, Federal, or Winchester cases, CCI or Winchester Large Rifle primers, 44.0 grains Varget, and the 200-grain Hornady FTX bullet. Manual shows this load as working with the 210-grain bullet as well, so loaded five 210-grain Nosler Partitions from RV in Federal cases, and five in Browning cases using that same 44.0 charge.
Results at 100 yards:
With Federal cases
With Browning cases
As comparison, three of the standard load with the FTX bullet