I've used the 6.5x55 on moose, elk, deer and black bear. On moose, I've used both 160 and 140 grain (hornady interlocks), on the rest, only the 140 grain interlocks. The furthest moose 250+ yds was shot with the 140s, the closest, -25 yds with 160 grain. In both cases the animal went about 50yds and dropped dead by the time I got to them. The rifle was used by several others on those hunts to take other moose and a few elk. Not all of the animals were taken with one shot by the way and a few required several, the multi shot kills were all due to lack of experience and poor target aquisition for whatever reason. I would in no way feel undergunned with a 6.5x55 for moose out to 400yds (highly unlikely range). As always, you must know your rifle well and it's trajectory with any given bullet. Next you must be calm enough when you pull the trigger, tom put the bullet in the kill zone. It really depends on you and the lengths that you're willing to go to get that shot. Yes, the 6.5x55 is more than adequate for moose. bearhunter