I've killed Bull Elk, 400 plus pound bears, Whitetails, Muleys, and Antelope and never had a need for anything heavier than 400 grains. I have shot heavier arrows, but I don't think they are needed.

Both heavy and Light arrows have their advantages and disadvantages. I prefer to stay away from both extremes. The Hunting arrows I used this year weighed 360 grains and I'd use them for anything in the US or Canada with confidence. A lot of variables in penetration results and just one of them is total weight of the arrow.

Dan