Should not be a problem for moose. Grizzly might be another matter depending on the situation. Never used one on Grizz. When I lived in AK I loaded Barnes X Bullets in my 416 Remmy. I like how they penetrate. Just my .02.
The north side of the grand mesa will be good. Look into 421 as well lots of good areas there. Definitely confirm your target as there are plenty of moose in the area as well.
Anywhere in western Colorado has Elk. Use a well constructed bullet and use a heavy for caliber bullets. I've used a 7-08 and .308 up to a 35 Whelen and 8mm Rem Mag. just keep distances reasonable. Elk can absorb a lot and still be on their feet.
Check out the Black Hills gold ammo or the Berger ammo which used to be ABM. go with a 175 grain or heavier bullet. Black hills had the ELD -X bullet and Berger is running several different Berger bullets.