I use "reject" heads from big game hunting, so long as they will hold a sharp edge, but prefer the big 3-blades like Snuffer. This annual discussion will lead eventually back to the old contest between full pass-through or keeping the arrow in the bird. I favor the latter, with arrow passing through but staying in the bird. But I hunt by roving public lands in mountain forests where, if the bird flies or runs, it almost always goes out of sight and finds a place to hide before you can recover it. The perfect set-up for me would be to nail 'em to a tree, or, as I did once, shoot from a strong vertical angle, such as a tree stand, so that the arrow sticks in the ground while still in the bird and prevents running or flying. Differnt ways of hunting may demand different strategies. But in any event, big heads are likely best for the big birds.