What exactly do you mean by free ranging? Some people mean their back yard. Me, when I free range- they are open to the ranch.
A LOT depends on your predators. Coons and coyotes have taken a lot of birds. I have tried changing the colors. I have heard that white birds are easily seen, and caught. I tried brown birds for camouflage, but now think that looks more like natural prey. I have recently read black birds, because they resemble crows, and that helps.
Truthfully, I have fed a lot of predators.
As for saving on commercial feed. I live in SD, and really while my birds scratch all year, May and June will produce enough food where it diminishes the need for commercial feed, by July, the bugs are hardening off- reach adult size, and not so much protien.
I randomly free range. I love to let them out. But if I do it every day, they pick me off.
Mrs K