I have to mostly agree with all that has been posted. I for one would hesitate to shoot at a moose at 300-400 yards unless it is really open country. In a lot of moose country it would be very easy to lose a moose if it wandered at all after a hit, or if hit poorly. I'm sure several are taken every year at these ranges but I'd recommend getting a lot closer in 99% of the cases. Regarding calibers, if you want something more than 30 cal, like one poster said, the 35 Whelen is a good one, I have friends who love the old 375 H&H, and the 338 Win Mag is very popular in Alaska. A lot of Alaska moose are taken with 270, 7mm mag, 308, 30-06, 300 mags. Being able to shoot it well, placing the bullet properly is the key like GB said. I have taken 1 moose with a 30-30, 3 with a 300 win mag. None very big.