My idea of choosing arrow weight is simple: Light for target shooting (under 7 grains per pound). Medium weight for anything up to deer size game (7-9 grains per pound). Heavy for game the size of elk and bigger (Over 9 grains per pound).

Since I don't like to swap around a whole lot with arrow weights, and I like having plenty of 'punch' for hog hunting, I like to do ALL my shooting with arrows weighing around 10 grains per pound of draw weight, although I'll go as light as 9 and as heavy as 12 sometimes, depending on what the bow likes. And I've still got more tournament trophies than I know what to do with.

The heavier the poundage you shoot, the longer your draw length and the higher performance the bow is, you can go lighter on arrow weight and still get adequate performance on game.

Even though an arrow at 5-6 grains per pound will often work fine for someone shooting a 70 pound, hard cam bow at 30" draw length, I simply feel that doing so is taking unjustified chances on getting bad penetration. And when the people that do so get those good results and tell people with shorter draw lengths and less poundage that they can expect good results at the same arrow weight/draw weight ratio, it's nothing short of criminal.