The 400gr. at 2,150fps did work well on moose, but i preferred the 350gr. RN Hornady at 2,296gps.
I had settled on 1 load for all bullet weights in the 2".
68gr. H335 and 56gr. IMR4320.
This load produced:
2,296fps w/ 350 Horn RN
2,150fps w/ 400gr. Barnes Spitzer also used 51.5gr. Re#7 same bal.
2,059fps w/ 500gr. Horn RN

I vould never understand the sub 2,000fps with the .458 Mag. since i exceeded the original "factory" ballistics using Barnes .458 data in my .458 Alaskan.
It is possible my pressures were "up there", but I never had and brass trouble. I used .338 Win. Mag. And .458 Win. Mag. brass.